fix: Fix action holder form buttons (ietf-tools#3956)

Fixes ietf-tools#3943

Author: larseggert

ietf/static/js/edit_action_holders.js

@@ -1,5 +1,5 @@
 local_js = function () {
-    let select2_elem = $('.select2-field');
+    let select2_elem = $('#id_action_holders');
     let role_ids = select2_elem.data('role-ids');
 
     function update_selection(elem, entries, selected) {
@@ -82,4 +82,4 @@ local_js = function () {
         add_ah: add_ah,
         del_ah: del_ah
     };
-}();
+}();