Backup review and wiki MySQL DBs.

* modules/openstack_project/manifests/review_dev.pp: Remove
mysql_backup, gerrit.pp will do this for review_dev now.

* modules/openstack_project/manifests/gerrit.pp: Put MySQL backups in
central Gerrit manifest. This will backup MySQL locally for review and
review-dev.

* modules/openstack_project/manifests/wiki.pp: Backup wiki MySQL DB
locally wth the mysql_backup module.

These changes make it possible to do offsite DB backups with bup by
first backing up the databases locally.

Change-Id: I932b439c153e461fa9c6b454e132137949bd08df
Merge "Backup review and wiki MySQL DBs."