ci: re-run checks for the newly applied labels

check.yml only runs on opened/synchronize/reopened, so the host-gated
job this change is about does not start from labelling alone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W14eEfXdK5DYzv43MazryE

Author: claude