Fix mariadb backup not working

This trivial fix simply consists of
adding the forgotten action after
the kolla-ansible was reworked in review [1].

[1] https://review.opendev.org/c/openstack/kolla-ansible/+/911417

Closes-Bug: #2080408
Change-Id: I26b5db3a3eeebd758ad05d9cb9aa689a68e1816f

ansible/roles/mariadb/tasks/backup.yml

@@ -2,6 +2,7 @@
 - name: Get MariaDB container facts
   become: true
   kolla_container_facts:
+    action: get_containers
     container_engine: "{{ kolla_container_engine }}"
     name:
       - "{{ mariadb_services.mariadb.container_name }}"

releasenotes/notes/bug-2080408-b25015799c646b13.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fixes mariadb backup.
+    `LP#[2080408] <https://launchpad.net/bugs/2080408>`__