Mark propagate labels as experimental

[Danil-Grigorev]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #560

Special notes for your reviewer:

Checklist:

• [ ] squashed commits into logical changes
• [ ] includes documentation
• [x] adds unit tests
• [ ] adds or updates e2e tests