[kayx23]

Why this PR is needed

Kubernetes discovery TEST 3 intentionally configures sample.com:6443 to verify resolved custom/default configuration values. That host is not the API server forwarded by CI, so the informer is expected to log a connection error. The default Test::Nginx no_error_log: [error] assertion makes the test fail depending on when the asynchronous informer attempt lands.

This backports the exact test-only fix from #13701: keep alert-level protection while allowing the expected connection error. Product code and response assertions are unchanged.

#14083 should rebase after this prerequisite merges.

Validation

• one commit changing only t/kubernetes/discovery/kubernetes.t
• git diff --check origin/release/3.17...HEAD
• exact upstream test-only change from test(kubernetes): stop TEST 3 failing on the expected apiserver connect error #13701
• full CI is running

[kayx23]

Closing this PR to keep the Admin API migration scoped to documentation and CI environment maintenance. This test-only backport was opened in response to an unrelated flaky check on a documentation PR; the documentation contract remains version-specific and is validated against its own branch sources.