[davidgamero]

summary

adds focused coverage on top of kubernetes-client#3078 for:

• cancellation through the legacy authProvider.config.exec form
• abort-listener cleanup after credential process close
• certificate/key credentials not being projected after cancellation
• preservation of a custom abort reason
• explicit POSIX negative process-group targeting, with the direct-child Windows branch encoded in the same test

validation

• focused source tests: 8 passed
• transpiled focused tests on Node 22: 8 passed
• npm run build-with-tests
• npm run lint
• git diff --check

this PR intentionally contains tests only; it is based directly on the current head of kubernetes-client#3078.