post new gh comment for PR deployment URL on second deployment

[atlasgong]

recreate:

1. create PR
2. deployment passes and the gh-actions bot posts a comment like this one: https://github.com/atlasgong/mindvista/pull/165#issuecomment-2790682099
3. make another push to the PR
4. a second deployment is created
5. the URL is not updated.

expected behaviour:
5. the URL should be updated to now redirect to the new deployment, and the prev one should be deleted.
6. a second comment should be posted with the exact same text and the old one should be hidden

now as I'm typing this issue out I realize we could just run the cleanup PR workflow if we detect it's a second deployment, and then run the check. or in fact we could just always run cleanup PR workflow before creating the redirect and comment, and set continue-on-error or have some other smoother error handling in PR checks for the cleanup workflow call