Replace test-summary action with custom action code

[ScottDugas]

The test-summary action takes the xml files produced by the tests, but our xml files in the nightly action get too large for the action to load them as a string (~540mb), due to all the logging.
This replaces the test-summary action with built-in steps that print to GITHUB_STEP_SUMMARY. They use the listener to gather the test results and exceptions.

You can see two examples of PRBs with the resulting output. Both of these disable many of the tests so that I could iterate more quickly:

• A successful run: https://github.com/ScottDugas/fdb-record-layer/actions/runs/13246744981
• A run with some failures: https://github.com/ScottDugas/fdb-record-layer/actions/runs/13246749305

I think there's two followups that could be nice, but decided not to do them right now:

1. It would probably make sense to remove all the destructiveTest runs from the summary that have 0 tests in them, which would make that table much smaller.
2. It would probably make sense to trim the stack traces to remove a whole slew of junit code.