Migrate from inline tests (tests/) to external test repository
(gitlab.com/redhat/centos-stream/tests/linuxptp).
- Add .fmf/version, ci.fmf, plans.fmf
- Update gating.yaml with tier1 public/internal references
- Remove tests/ directory (moved to test repo)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
