Polish agent checkpoints (#29265)

Release Notes:

- Improved performance of agent checkpoint creation.
- Fixed a bug that sometimes caused accidental deletions when restoring
to a previous agent checkpoint.
- Fixed a bug that caused checkpoints to be visible in the Git history.
e515b2c714Antonio Scandurra committed on 4/23/2025, 11:37:55 AM· committed by GitHubparent55ea481
4 files changedLine totals unavailable