GitHub board automation: remove redundant event handling (#56429)

We shouldn't trigger this workflow on pull_request_review.submitted
because (1) two out of three possible cases here are already handled by
the build-in workflow automation of the project board itself, and (2)
this takes us into the territory of workflow runs that require approval.

Release Notes:

- N/A
a3781513baLena committed on 5/11/2026, 3:12:37 PM· committed by GitHubparent7813573
2 files changedLine totals unavailable