Improves the MariaDB wait command to use mariadb-admin ping for a better check if the server is up (#11396)

docker/rootfs/etc/s6-overlay/s6-rc.d/init-wait-for-db/run

@@ -51,7 +51,7 @@ wait_for_mariadb() {
 	local -r host="${PAPERLESS_DBHOST:-localhost}"
 	local -r port="${PAPERLESS_DBPORT:-3306}"
 
-	while ! true > "/dev/tcp/$host/$port"; do
+	while ! mariadb-admin --host="$host" --port="$port" ping --silent >/dev/null 2>&1; do
         delay_next_attempt
 	done
 	echo "${LOG_PREFIX} Connected to MariaDB"