Since the callbacks from onAtomicSectionCancel() run during complex internal state updates within "critical sections" with Database, it is very hard to reason about callbacks that go back into the database trying to retry queries. Not to mention all of this stuff can be wrapped in multi-connection transaction rounds on the LBFactory level.

Ideally, onAtomicSectionCancel() should also be deprecated to avoid further callers.

This came up during the investigation of T368289.