[Nextcloud] Always install under subdomain, minor changes to site config and install script

data/assets/nextcloud/occ

@@ -1,2 +1,2 @@
 #!/bin/bash
-docker exec -it -u www-data $(docker ps -f name=php-fpm-mailcow -q) /web/nextcloud/occ ${@}
+docker exec -it -u www-data $(docker ps -f name=php-fpm-mailcow -q) php /web/nextcloud/occ ${@}