Revert "ci: suppress redundant tests runs on PR and push"
It turns out doing CI on review_requested is not great, because:
- if you request 2 or 3 reviews, it triggers the action 2 or 3 times
- when the branch needs a real merge, we do want the result of the merge
tested in CI, so we lost important validation
This reverts commit 91f4a35307abfef8906c59367793681ea4712938.
