[mergebot] Fix for pagination error (#95333)
Fix for weird bug that happens very rarely. My solution is to retrieve all checksuites before going to retrieve their checkruns.
Sometimes `cs_cursor=edges[edge_idx - 1]["cursor"] if edge_idx > 0 else None,` is None when it shouldn't be because of how we reset `checksuites = get_next_checksuites(checksuites)` on every loop.
Ex
page 1 of checksuites contains some stuff
page 2 of checksuites: pull {a bunch of checkruns}
cs_cursor gets set to none for the pull checksuite on page 2 because `checksuites = get_next_checksuites(checksuites)` resets the edges on every loop. Then the checkruns can't be retrieved.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95333
Approved by: https://github.com/huydhn
