roles/mariadb: Update service name

As of MariaDB 10.5 the service name and binaries have changed from
mysql, mysqld, etc to mariadbd.

See: https://mariadb.com/kb/en/upgrading-from-mariadb-104-to-mariadb-105/

roles/mariadb/tasks/main.yml

@@ -26,7 +26,7 @@
 - name: Create system my.cnf
   template: src=my.cnf.j2 dest=/etc/mysql/my.cnf owner=root group=root mode=0644
   notify:
-    - restart mysql
+    - restart mariadbd
   tags: mariadb
 
 # 'localhost' needs to be the last item for idempotency, see