Remove transitionend event from GL dropdown

app/assets/javascripts/gl_dropdown.js

@@ -300,7 +300,7 @@ GitLabDropdown = (function() {
             return function(data) {
               _this.fullData = data;
               _this.parseData(_this.fullData);
-              _this.focusTextInput(true);
+              _this.focusTextInput();
               if (_this.options.filterable && _this.filter && _this.filter.input && _this.filter.input.val() && _this.filter.input.val().trim() !== '') {
                 return _this.filter.input.trigger('input');
               }
@@ -790,24 +790,16 @@ GitLabDropdown = (function() {
     return [selectedObject, isMarking];
   };
-  GitLabDropdown.prototype.focusTextInput = function(triggerFocus = false) {
+  GitLabDropdown.prototype.focusTextInput = function() {
     if (this.options.filterable) {
-      this.dropdown.one('transitionend', () => {
-        const initialScrollTop = $(window).scrollTop();
-        if (this.dropdown.is('.open')) {
-          this.filterInput.focus();
-        }
-
-        if ($(window).scrollTop() < initialScrollTop) {
-          $(window).scrollTop(initialScrollTop);
-        }
-      });
-      if (triggerFocus) {
-        // This triggers after a ajax request
-        // in case of slow requests, the dropdown transition could already be finished
-        this.dropdown.trigger('transitionend');
+      const initialScrollTop = $(window).scrollTop();
+      if (this.dropdown.is('.open')) {
+        this.filterInput.focus();
+      }
+      if ($(window).scrollTop() < initialScrollTop) {
+        $(window).scrollTop(initialScrollTop);
       }
     }
   };