[mergebot] set on green to true if it has ciflow (#82110)
### Description
<!-- What did you change and why was it needed? -->
We've had reports of people adding ciflow labels and then merging with the expectation that it wouldn't merge until everything was passing. This wasn't how merge worked because it only works for mandatory jobs, so now based on that feedback, we're waiting for all jobs if there's a ciflow/* label on the PR.
### Issue
<!-- Link to Issue ticket or RFP -->
n/a
### Testing
<!-- How did you test your change? -->
let tests run
Ran the trymerge locally and checked that on_green was true/false depending if the ciflow label was added
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82110
Approved by: https://github.com/ZainRizvi, https://github.com/malfet, https://github.com/huydhn
