Remove ui-state-active from siblings of the expanded menu item

Previously when a menu item was expanded the class `ui-state-active` was
not removed from the previous expanded menu item. This resulted in two
(or more if you expanded more) menu items with this class.

Author: arnoudhgz

Diff for: lib/web/mage/menu.js

@@ -626,6 +626,9 @@ define([
                     return;
                 }
 
+                // remove the active state class from the siblings
+                this.active.siblings().children('.ui-state-active').removeClass('ui-state-active');
+
                 this._open(newItem.parent());
 
                 // Delay so Firefox will not hide activedescendant change in expanding submenu from AT