Ticket 48964 - cleanAllRUV changelog purging incorrectly
processes all backends
Bug Description: When the changelog was being purged of "cleaned" rids it was checking
all the backend changelogs, and not the one from which the
cleanAllRUV task originated from. This could corrupt a different
backend's changelog if both backends used the same RID.
Fix Description: Purge the changelog associated with the backend that is specified in
the cleanAllRUV task. Also moved the "purging" to its own function,
and fixed a few compiler warnings.
Reviewed by: nhosoi(Thanks!)
(cherry picked from commit fda00435a7536c1ded72bb78a975f3370d09a3be)