T9220: ci: upload JUnit test results to Codecov Test Analytics (#497)

• T9220: ci: upload JUnit test results to Codecov Test Analytics (probe)

Wire pytest JUnit XML output and a pinned codecov-action@v5.5.5
test-results upload step (tokenless, informational) as the public-class
PF-B probe for the Codecov Test Analytics fleet rollout.

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• T9220: ci: continue-on-error on test-results upload (informational posture)

A step timeout would fail the job despite fail_ci_if_error: false;
continue-on-error keeps the upload strictly informational.

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• T9220: ci: fold test-results upload condition (yaml line-length)

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