Update excluded_substring_map to use setdefault and extend

[emmuhamm]

Description

This is related to DUNE-DAQ/drunc#932, which came about from DUNE-DAQ/drunc#930

When fixing some of the new behaviour in drunc, I needed to add this line (see comment) to ignored_logfile_problems.

However, I noticed that this wasn't working because the relevant line in src/integrationtest/log_file_checks.py is continuously overriding this. This change fixes it to properly set a default as written there, but also to respect if others wanted to add their own stuff to ignore by appending the list.

Type of change

• Optimization (non-breaking change that improves code/performance)

Testing checklist

- [ ] Unit tests pass (e.g. dbt-build --unittest)

• Minimal system quicktest passes (pytest -s minimal_system_quick_test.py)
  - [ ] Full set of integration tests pass (dunedaq_integtest_bundle.sh)
  - [ ] Python tests pass if applicable (e.g. python -m pytest)
  - [ ] Pre-commit hooks run successfully if applicable (e.g. pre-commit run --all-files)

Testing suggestion

This is tested with the relevant drunc PR. I recommend following the testing notes here DUNE-DAQ/drunc#933 to properly test the changes.

However, the minimal test that can be done is simply by running the msqt and seeing that nothing breaks.

Further checks

• Code is commented where needed, particularly in hard-to-understand areas
• Code style is correct (dbt-build --lint, and/or see https://dune-daq-sw.readthedocs.io/en/latest/packages/styleguide/)
• If applicable, new tests have been added or an issue has been opened to tackle that in the future.
  (Indicate issue here: # (issue))

[emmuhamm]

Hi @bieryAtFnal, I've added this PR here to fix a small bug I encountered when running the PM integ test in drunc. Can you have a look at it? All relevant information should be in the desc.

[bieryAtFnal]

This looks good to me. I ran a test in which I saw the expected (now corrected) behavior. Thanks for the fix!