Added variables ``galera_backups_full_init_overrides`` and
``galera_backups_increment_init_overrides`` that can be leveraged to
override default set of systemd unit file for mariadb backups.
Change-Id: Ib15c60dc577b376b1f761c4266eea89c4cb0be9f
(cherry picked from commit 3e2afc1e4edb152693d4e77a35340791dc80e408)
(cherry picked from commit b5f4e4d737f4a2f8fc6ded3639904b7e429048d9)