HDDS-14072. Show structured test summary in CI result

[chihsuan]

What changes were proposed in this pull request?

This PR implements the structured CI test summaries described in HDDS-14072.

• Add dev-support/ci/junit_summary.py, a stdlib-only parser for Maven Surefire and Failsafe XML reports.
• Append a structured Markdown test summary to the GitHub Actions job summary.
• Recognize Surefire <flakyFailure> and <flakyError> elements as tests that recovered on rerun.
• Add a quarantined-test table for the test-flaky split.
• Register the parser unit tests with the existing Bats check through dev-support/ci/junit_summary.bats.

The generated summary includes:

• total test count and cumulative test time
• passed, failed, flaky, and skipped counts
• details for failed, flaky, and skipped tests
• a link to the archived test reports

Report discovery handles both normal module report directories and failed reports moved under target/<check>/. Iteration directories are excluded to avoid counting repeated runs multiple times.

Operational behavior

The summary is informational and cannot fail an otherwise successful check:

• malformed or unreadable reports are skipped
• the script always exits with status 0
• the workflow step also uses continue-on-error: true
• jobs without JUnit XML produce no summary

The parser uses Python's standard xml.etree.ElementTree. The input is generated by Maven in the same CI job, so no additional XML dependency is needed.

Out of scope

• deriving a quarantine table from @Flaky and @Unhealthy annotations
• Kafka-style new-test detection
• aggregating all splits into one PR-level report
• enabling rerunFailingTestsCount outside the flaky split

What is the link to the Apache JIRA?

https://issues.apache.org/jira/browse/HDDS-14072

How was this patch tested?

• python3 -m unittest test_junit_summary -v: 16 tests passed
• rat.sh: passed
• checkstyle.sh: passed
• Local Surefire smoke test with TestOzoneConfiguration: rendered 48 passing tests
• Full fork CI run: all checks passed
  • non-test jobs produced no output
  • integration summaries included pass and skipped-test details
  • the flaky split reported 162 passed and 5 flaky tests, confirming real Surefire rerun detection
  • zizmor passed for the workflow change

Generated-by: Claude Code (Opus 4.8)

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