Use Search API for hotfix monitor to avoid job cancellation (#51880)

## Summary

- The Pulls API with `state=closed` paginates through all closed PRs in
the repo. On a repo as active as Zed, this exceeds the 5-minute job
limit ([failed
run](https://github.com/zed-industries/zed/actions/runs/23271617583)).
- Switch to the Search API which supports `merged:>DATE` natively, so
GitHub filters server-side and returns only matching hotfix PRs.
- Tested against the Zed repo — query completes in seconds.

Release Notes:

- N/A
953d87d63bJohn D. Swanson committed on 3/18/2026, 11:32:38 PM· committed by GitHubparent695382e
1 file changedLine totals unavailable