Timeouts in a test case in `rpc_fundrawtransaction` #21452

Since the merge of 48a0319bab in #20536 on March 8, 2021, test/functional/rpc_fundrawtransaction.py raises locally when run with the test runner

File "/home/jon/projects/bitcoin/bitcoin/test/functional/rpc_fundrawtransaction.py", line 927, in test_transaction_too_large
raise JSONRPCException({
    test_framework.authproxy.JSONRPCException: 'generatetoaddress' RPC took longer than 30.000000 seconds. Consider using larger timeout for calls that take longer to return. (-344)

and in the CI like https://bitcoinbuilds.org/index.php?ansilog=28537952-2c92-46f2-9871-8918e5ba2738.log#l2398

File "/home/ubuntu/src/test/functional/rpc_fundrawtransaction.py", line 927, in test_transaction_too_large
test_framework.authproxy.JSONRPCException: 'generatetoaddress' RPC took longer than 240.000000 seconds. Consider using larger timeout for calls that take longer to return. (-344)

One solution is proposed in #21410, which increases the rpc_timeout value from the default value of 60 seconds to 90 (a previous version was 120). This is a small increase relative to other tests that increase the value to 120, 240, or 480 seconds, but in my testing it seems to be sufficient to resolve this issue for me locally and also in bitcoinbuilds where it previously passed as well:

• https://bitcoinbuilds.org/?build=8266 (rpc_timeout = 480)
• https://bitcoinbuilds.org/?build=8392 (rpc_timout = 120)
• https://bitcoinbuilds.org/?build=8465 (rpc_timeout = 90)

I hit this issue every day when testing pull requests, and it would be great to see it resolved.

Tentatively closing after the merge of #21410, but as mentioned in #21410 (comment) this may need a deeper look into why generating a few blocks here required more than 60 seconds.