Prune Test Suites and Fix CI

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.

Merged #5585 (deploy green). CI reds since 10-13 traced: rest fixed upstream; fixed the 2 open flakes by induction (Login stale-snapshot bounce = product fix; node tab strip). Dropped 1 duplicated e2e spec; 2 quick stages cheaper (4.4→1.0s, 4.0→2.4s); regroup: none qualifies. Full gate pass 532s. Relied on mem-2.