Address GHA prompting workflows duplicate comment behavior

[ezekiel]

We use workflows that recognize certain types of changes and add comments to prompt for specific actions ( see https://github.com/letsencrypt/boulder/blob/main/.github/workflows/cps-review.yml, and https://github.com/letsencrypt/boulder/blob/main/.github/workflows/issue-for-sre-handoff.yml ).

When a WIP pull request is marked ready-for-review, these workflows can double-comment.

There may be other cases where duplication can happen. Let's see if we can de-duplicate.

[aarongable]

For context: to the best of my knowledge, the double-commenting is because the workflows trigger on the draft->ready state transition, and that transition also causes a reviewer to be assigned from our CODEOWNERS file, which also triggers the workflow.