WT-7733Flush tier should skip flushing tables and switching object for
tables that have not changed since the previous flush tier call.
- Reduce or eliminate some sleep calls.
- Fix verbose type.
- Fix usage of time saving for flushing and comparison with checkpoint
- Remove unused comment. Fix test to reopen the connection.
- Clean up test.
- Don't allow checkpoint times to move backward.
- Add checkpoint lock comments.
- ckpt->sec can never be less than most-recent. Fix <= to ==. | 18 Nov 21 14:02 UTC
Evergreen Subscription: ; Evergreen Event: