Merge "Fix deploy-containers command for mariadb"

ansible/roles/mariadb/tasks/bootstrap.yml

 ---
-- set_fact:
+- name: Set a fact about the master host
+  set_fact:
     master_host: "{{ groups['mariadb'][0] }}"
 
 - include_tasks: lookup_cluster.yml

ansible/roles/mariadb/tasks/deploy-containers.yml

 ---
+- name: Set a fact about the master host
+  set_fact:
+    master_host: "{{ groups['mariadb'][0] }}"
+
 - import_tasks: check-containers.yml