test: Bump sync_mempools timeout in p2p_1p1c_network.py #31701

This should address the two issues that happened in https://github.com/bitcoin/bitcoin/actions/runs/12885576442/job/35924329657?pr=25832#step:6:7601:

• The combined log isn't printed on a test failure.
• The timeout is too strict for the GHA virtual machines.

For reference, the output was:

...
149/315 - rpc_blockchain.py --v2transport passed, Duration: 10 s
150/315 - p2p_addrfetch.py passed, Duration: 1 s
151/315 - p2p_1p1c_network.py failed, Duration: 31 s

stdout:
2025-01-21T12:05:49.465000Z TestFramework (INFO): PRNG seed is: 6581340712385622842
2025-01-21T12:05:49.466000Z TestFramework (INFO): Initializing test directory /tmp/test_runner_₿_🏃_20250121_120233/p2p_1p1c_network_207
2025-01-21T12:05:52.408000Z TestFramework (INFO): Fill mempools with large transactions to raise mempool minimum feerates
2025-01-21T12:05:52.408000Z TestFramework (INFO): Fill the mempool until eviction is triggered and the mempoolminfee rises
2025-01-21T12:05:59.692000Z TestFramework (INFO): Pre-send some transactions to nodes
2025-01-21T12:06:00.203000Z TestFramework (INFO): Submit full packages to node0
2025-01-21T12:06:00.220000Z TestFramework (INFO): Wait for mempools to sync
2025-01-21T12:06:20.384000Z TestFramework (ERROR): Assertion failed
Traceback (most recent call last):
  File "/home/runner/work/bitcoin/bitcoin/test/functional/test_framework/test_framework.py", line 135, in main
    self.run_test()
  File "/home/runner/work/bitcoin/bitcoin/build/test/functional/p2p_1p1c_network.py", line 153, in run_test
    self.sync_mempools(timeout=20)
  File "/home/runner/work/bitcoin/bitcoin/test/functional/test_framework/test_framework.py", line 803, in sync_mempools
    raise AssertionError("Mempool sync timed out after {}s:{}".format(
AssertionError: Mempool sync timed out after 20s:
...

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31701.

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ACK fa80a7dac4be8a1d8e32d88e46da23f14e06bade

Makes sense to me. There are 4 nodes on p2p_1p1c_network, so makes sense that it could take longer than 20sec for everything to propagate. Default is 60 iirc?

utACK fa80a7dac4be8a1d8e32d88e46da23f14e06bade

Same happened in https://github.com/bitcoin/bitcoin/actions/runs/12888898958/job/35934893317?pr=31699

Looks like this still happens: #31713 (comment)

So this is likely a non-timeout issue. Note that the test has immediate tx-relay (self.noban_tx_relay) enabled, so trickle delay should not be an issue.