Fix security issue when using list functionality via api.php

Remote code execution could have been triggered by activating some list
functionality (add and remove) via api.php.

Thanks to Kacper Szurek for finding this bug.

Signed-off-by: Mcat12 <newtoncat12@yahoo.com>

scripts/pi-hole/php/auth.php

@@ -142,14 +142,5 @@ function list_verify($type) {
     {
         log_and_die("Not allowed!");
     }
-
-    // Don't check if the added item is a
-    // valid domain for regex expressions
-    // Regex filters are validated by FTL
-    // on import and skipped if invalid
-    if($_POST['list'] !== "regex")
-    {
-        check_domain();
-    }
 }
 ?>