- Part of #1833.
- CLI progress and registry test migrations were inadventently reverted
by #1857.
- Migrate TestCLINoParallelCases to TestCLIImagePruneSerial and
TestCLINetworkPruneSerial.
- Clean up test selection patterns in Makefile.
- Remove all legacy CLITests files.
- Use swift-testing `withKnownIssue` to run but ignore failures on flaky
`testCreateNameLongestValid` and `testIsolatedNetwork`.
- Extracts a fixture helper for tests requiring a retry loop.