test: Test new header sync behavior in loadtxoutset #29478

It adds a test for the change to loadtxoutset made in #29345. Before that change the test doesn't fail right away but times out after 10 minutes.

Also removes a sync_blocks call that didn't seem to do anything valuable.

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #29612 (rpc: Optimize serialization disk space of dumptxoutset - Reloaded by fjahr)
• #29553 (assumeutxo: Add dumptxoutset height param, remove shell scripts by fjahr)
• #29370 (assumeutxo: Get rid of faked nTx and nChainTx values by ryanofsky)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

rebased

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🚧 At least one of the CI tasks failed. Make sure to run all tests locally, according to the documentation.

Possibly this is due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

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_{Debug: https://github.com/bitcoin/bitcoin/runs/21991913561}

tACK 1ec6684b08614f593b37e627a0a08e54b19318b6

<details>

<summary>Since this PR is based on top of [#29345](/bitcoin-bitcoin/29345/), I've backed it out from <code>src/rpc/blockchain.cpp</code> in order to hit the mentioned <code>timeout</code>.</summary>

git log --oneline src/rpc/blockchain.cpp
faa30a4c56 (2401-rpc-loadtxoutset-) rpc: Do not wait for headers inside loadtxoutset
fa9108941f rpc: Fix race in loadtxoutset

git checkout fa9108941fa1a0e83484114e2d8a99d264c2ad09 -- src/rpc/blockchain.cpp

• Note: a reviewer could extend the timeout changing self.rpc_timeout on test/functional/feature_assumeutxo.py

./test/functional/feature_assumeutxo.py 
2024-02-27T16:30:31.156000Z TestFramework (INFO): PRNG seed is: 1857178557572365167
2024-02-27T16:30:31.157000Z TestFramework (INFO): Initializing test directory /tmp/bitcoin_func_test_7fznd8ax
2024-02-27T16:30:32.583000Z TestFramework (INFO): -- Testing assumeutxo + some indexes + pruning
2024-02-27T16:30:32.584000Z TestFramework (INFO): Creating a UTXO snapshot at height 299
2024-02-27T16:30:32.619000Z TestFramework (INFO): Test loading snapshot when headers are not synced
2024-02-27T16:31:32.679000Z TestFramework (ERROR): Assertion failed
Traceback (most recent call last):
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/authproxy.py", line 151, in _get_response
    http_response = self.__conn.getresponse()
  File "/usr/lib/python3.10/http/client.py", line 1375, in getresponse
    response.begin()
  File "/usr/lib/python3.10/http/client.py", line 318, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python3.10/http/client.py", line 279, in _read_status
    line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")
  File "/usr/lib/python3.10/socket.py", line 705, in readinto
    return self._sock.recv_into(b)
TimeoutError: timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/util.py", line 140, in try_rpc
    fun(*args, **kwds)
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/coverage.py", line 50, in __call__
    return_val = self.auth_service_proxy_instance.__call__(*args, **kwargs)
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/authproxy.py", line 127, in __call__
    response, status = self._request('POST', self.__url.path, postdata.encode('utf-8'))
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/authproxy.py", line 106, in _request
    return self._get_response()
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/authproxy.py", line 153, in _get_response
    raise JSONRPCException({
test_framework.authproxy.JSONRPCException: 'loadtxoutset' RPC took longer than 60.000000 seconds. Consider using larger timeout for calls that take longer to return. (-344)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/test_framework.py", line 131, in main
    self.run_test()
  File "/home/pablo/workspace/bitcoin/./test/functional/feature_assumeutxo.py", line 191, in run_test
    self.test_headers_not_synced(dump_output['path'])
  File "/home/pablo/workspace/bitcoin/./test/functional/feature_assumeutxo.py", line 118, in test_headers_not_synced
    assert_raises_rpc_error(-32603, "The base block header (3bb7ce5eba0be48939b7a521ac1ba9316afee2c7bada3a0cca24188e6d7d96c0) must appear in the headers chain. Make sure all headers are syncing, and call this RPC again.",
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/util.py", line 131, in assert_raises_rpc_error
    assert try_rpc(code, message, fun, *args, **kwds), "No exception raised"
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/util.py", line 144, in try_rpc
    raise AssertionError("Unexpected JSONRPC error code %i" % e.error["code"])
AssertionError: Unexpected JSONRPC error code -344
2024-02-27T16:31:32.741000Z TestFramework (INFO): Stopping nodes
2024-02-27T16:31:32.742000Z TestFramework.node1 (ERROR): Unable to stop node.
Traceback (most recent call last):
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/test_node.py", line 377, in stop_node
    self.stop(wait=wait)
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/coverage.py", line 50, in __call__
    return_val = self.auth_service_proxy_instance.__call__(*args, **kwargs)
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/authproxy.py", line 127, in __call__
    response, status = self._request('POST', self.__url.path, postdata.encode('utf-8'))
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/authproxy.py", line 105, in _request
    self.__conn.request(method, path, postdata, headers)
  File "/usr/lib/python3.10/http/client.py", line 1283, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib/python3.10/http/client.py", line 1294, in _send_request
    self.putrequest(method, url, **skips)
  File "/usr/lib/python3.10/http/client.py", line 1120, in putrequest
    raise CannotSendRequest(self.__state)
http.client.CannotSendRequest: Request-sent
2024-02-27T16:32:32.889000Z TestFramework.utils (ERROR): wait_until() failed. Predicate: ''''
        self.wait_until(lambda: self.is_node_stopped(expected_ret_code=expected_ret_code, **kwargs), timeout=timeout)
'''
Traceback (most recent call last):
  File "/home/pablo/workspace/bitcoin/./test/functional/feature_assumeutxo.py", line 370, in <module>
    AssumeutxoTest().main()
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/test_framework.py", line 154, in main
    exit_code = self.shutdown()
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/test_framework.py", line 313, in shutdown
    self.stop_nodes()
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/test_framework.py", line 578, in stop_nodes
    node.wait_until_stopped()
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/test_node.py", line 425, in wait_until_stopped
    self.wait_until(lambda: self.is_node_stopped(expected_ret_code=expected_ret_code, **kwargs), timeout=timeout)
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/test_node.py", line 802, in wait_until
    return wait_until_helper_internal(test_function, timeout=timeout, timeout_factor=self.timeout_factor)
  File "/home/pablo/workspace/bitcoin/test/functional/test_framework/util.py", line 276, in wait_until_helper_internal
    raise AssertionError("Predicate {} not true after {} seconds".format(predicate_source, timeout))
AssertionError: Predicate ''''
        self.wait_until(lambda: self.is_node_stopped(expected_ret_code=expected_ret_code, **kwargs), timeout=timeout)
''' not true after 60 seconds
[node 2] Cleaning up leftover process
[node 1] Cleaning up leftover process

</details>

lgtm

ACK 1ec6684b08614f593b37e627a0a08e54b19318b6

Looks good to me

ACK 1ec6684b08614f593b37e627a0a08e54b19318b6

ACK 1ec6684b08614f593b37e627a0a08e54b19318b6