Added healthcheck for mariadb

roles/docker-nextcloud/templates/docker-compose.yml.j2

@@ -28,6 +28,11 @@ services:
     volumes:
       - database:/var/lib/mysql
     restart: always
+    healthcheck:
+      test: "/usr/bin/mysql --user=nextcloud --password={{nextcloud_database_password}} --execute \"SHOW DATABASES;\""
+      interval: 3s
+      timeout: 1s
+      retries: 5
   web:
     image: nginx:alpine
     logging: