Add missing regex to backup manager
What does this MR do?
!10901 (merged) introduced a new naming scheme for backups, but the code which cleans up old backups wasn't updated accordingly. In order to maintain backward compatibility, we need to account for 3 naming schemes.
http://rubular.com/r/dUx1D42p3i
What are the relevant issue numbers?
Edited by Achilleas Pipinellis