fix(dropdownfield): wrong var in join

Signed-off-by: Thierry Bugier <[email protected]>

Author: btry

inc/fields/dropdownfield.class.php

@@ -484,7 +484,7 @@ private function getMyGroups($userID) {
             $groupTable => [
                'FKEY' => [
                   $groupTable => 'id',
-                  $groupUser => $groupFk,
+                  $groupUserTable => $groupFk,
                ],
             ],
          ],