[Web] Clean PHP code by removing unused variables (#3646)

* [WEB] $lang is not used in this context

* [Web] $stmt variable is not used

data/web/inc/functions.quota_notification.inc.php

@@ -1,7 +1,6 @@
 <?php
 function quota_notification($_action, $_data = null) {
 	global $redis;
-	global $lang;
 	$_data_log = $_data;
   if ($_SESSION['mailcow_cc_role'] != "admin") {
     $_SESSION['return'][] = array(