Changing max_connections to a .get()

max_connections were not being applied right.

galera/files/my.cnf

@@ -28,7 +28,7 @@ syslog
 datadir=/var/lib/mysql
 bind-address={{ service.bind.address }}
 port=3306
-max_connections={{ service.max_connections }}
+max_connections={{ service.get('max_connections', 200) }}
 default-storage-engine=innodb
 binlog_format=ROW
 collation-server=utf8mb4_unicode_ci