MT#58395 do not start mariadb with config connect method

* it's not a responsiblity of the script to start/stop
  any external services and therefore, mariadb start
  is removed

Change-Id: I220ebab7764a7016b15e6f08a8ac5ae01fe08523

ngcp-update-db-schema

@@ -358,7 +358,7 @@ def connect_db() -> Connection:  # type: ignore
         except pymysql.Error as e:
             error(
                 'could not connect to database %s:%d via socket %s as %s: %s' %
-                (db_host, db_port, db_connect_method, db_user, e)
+                (db_host, db_port, db_socket, db_user, e)
             )
             shutdown(1)
     elif db_connect_method == 'config':
@@ -376,17 +376,6 @@ def connect_db() -> Connection:  # type: ignore
             error(f'cannot access {db_defaults_conf_file}: {e}')
             shutdown(1)
 
-        cmd: List[str] = ['ngcp-service', 'start', 'mariadb']
-        try:
-            debug(f'run_cmd as: {cmd}')
-            stdout, stderr = run_cmd(*tuple(cmd))
-            log(stdout.decode())
-            if stderr:
-                raise ChildProcessError(stderr.decode())
-        except ChildProcessError as e:
-            error(f'could start mariadb service: {e}')
-            shutdown(1)
-
         try:
             db_conn: Connection = pymysql.connect(  # type: ignore
                 host=db_host,