Clean Up and Fix CI Tests

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 #6229 merged and deployed. Fixed the jaahd IPv6 flake behind the last two test.yml reds and deleted a never-run e2e spec; develop had already fixed every other red. Full gate green. A test.yml re-run needs the next master promotion PR.