use MariaDB style for database settings instead of Postgres

ansible/roles/apps/templates/wordpress-settings.yaml

@@ -44,10 +44,11 @@ database:
     password: "{{ wordpress_mariadb_password }}"
   rootUser:
     password: "{{ wordpress_mariadb_root_password }}"
-  persistence:
-    ## Enable PostgreSQL persistence using Persistent Volume Claims.
-    enabled: true
-    existingClaim: "wordpress-mariadb"
+  master:
+    persistence:
+      ## Enable MariaDB persistence using Persistent Volume Claims.
+      enabled: true
+      existingClaim: "wordpress-mariadb"
   replication:
     enabled: false