Add example ConnectionOverride and use it for the 3ru_1df_multirun_test

[eflumerf]

Description

This PR adds a ConnectionOverride object (DUNE-DAQ/confmodel#105) to the integration test configurations, and also configures ru-det-conn-1 in 3ru_1df_multirun_test to override its output connections to use 127.0.0.2 instead of 127.0.0.1.

Top-level PR: DUNE-DAQ/ipm#129

Type of change

• Documentation (non-breaking change that adds or improves the documentation)
• New feature or enhancement (non-breaking change which adds functionality)
• Optimization (non-breaking change that improves code/performance)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (whatever its nature)

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)

Comments here on the testing
Test case added to 3ru_1df_multirun_test.py in daqsystemtest to demonstrate directing a specific application's outputs to use an alternate output interface.

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))

[eflumerf]

Note that many of the OKS database changes in this PR are due to over-enthusiastic application of oks-format.