Test suite cleanup and CI pipeline stabilization

Review all test suites, delete stale, superseeded, those that were one off to check feature flags or absence of something. Kill the most long running or flaky with unit tests that execute in milliseconds. Regroup between quick and full, Fix broken tests in CI - GitHub Actions - look at a few recent test runs and fix broken/flaky tests. Babysit CI/CD until the tests (test.yaml) pass.

PR #6669 queued in the merge lane. CI and every suite green on develop (old reds were fixed regressions). Fixed a jaahd 20s message wait (20.2s→0.17s) and bounded the lock audit (1135s→≤300s); deleted 1 stale test. Deferred: Dockerfile.api apk stall. Memory: none applied.