Fixes to prevent duplicate rows in ActiveUser cache

* Handle repeatable-read snapshots better for web requests
* In CLI mode, handle automatic reconnects better (rolling
  back). It has to abort since it lost the lock in that case.

bug: 71086
Change-Id: I5228889cf05857c87a06f7d073b5aa46f0c240be
Merge "Fixes to prevent duplicate rows in ActiveUser cache"