Retry inserting into wb_entity_per_page table  on deadlock.

Inserts into the wb_entity_per_page table often fail with a deadlock error.
This change puts the insert into a retry loop to mitigate that problem.

Caveat: no unit test, since this only happens with an overloaded database.

Bug: 70400
Change-Id: If8f6a742ab8bb91825f99aff1086cc1ad440e138
Merge "Retry inserting into wb_entity_per_page table  on deadlock."