[GHA] Rectify `trigger_action_only` flag (#66209)
Summary:
No longer needed, as PR can be opened/reopened with specific label
Fixes https://github.com/pytorch/pytorch/issues/66110
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66209
Reviewed By: seemethere
Differential Revision: D31436292
Pulled By: malfet
fbshipit-source-id: 5b6e0875bec261862017dfe0eb3a5ec57fb8c705
