test: feature_llmq_connections.py intermittently times out waiting for DKG phase 2 under UBSan

[thepastaclaw]

Failure

feature_llmq_connections.py intermittently times out in the UBSan functional-test job while waiting for DKG phase 2 (receivedContributions).

Observed in CI for #7465:

• Failing job: https://github.com/dashpay/dash/actions/runs/29429137489/job/87405284152
• Check: linux64_ubsan-test / Test source
• Test runner retried the test three times; all three attempts failed after 140 s, 143 s, and 132 s.
• The final attempt reached DKG phase 1, then timed out waiting for phase 2 in wait_for_quorum_phase().
• Final-attempt PRNG seed: 3108379943187254370

The failure is unrelated to the triggering PR. Its diff only changes Qt font scaling and Qt unit-test files:

• src/Makefile.qttest.include
• src/qt/guiutil_font.cpp
• src/qt/test/fonttests.cpp
• src/qt/test/fonttests.h
• src/qt/test/test_main.cpp

There are no changes to feature_llmq_connections.py, the functional-test framework, or LLMQ source code.

Evidence of intermittency

The exact develop base (ca2912d9024836e825cdd3e8cc4db83926c3790f) passed the same UBSan test one day earlier:

• Successful base job: https://github.com/dashpay/dash/actions/runs/29358822835/job/87178697267
• feature_llmq_connections.py passed in 82 s.

The PR run's non-UBSan linux64-test / Test source job also passed:

• https://github.com/dashpay/dash/actions/runs/29429137489/job/87405606645

This points to a timing-sensitive DKG progress failure under sanitizer/resource contention rather than a deterministic product-code regression. The precise reason some members fail to enter/report phase 2 still needs investigation.

Reproduction

1. Build the linux64_ubsan CI target.

2. Run the extended functional suite under normal CI parallel load, or repeatedly run:

   python3 test/functional/feature_llmq_connections.py

3. Observe whether wait_for_quorum_phase() times out waiting for phase 2 / receivedContributions.

The CI job link above contains the consolidated node and test logs for the failed final attempt.