DEV: Change sidebar header dropdown to use wait_for_animation (#20627)

* DEV: Change sidebar header dropdown to use wait_for_animation

Introduced in 54351e1b8a, this
helper should remove the need to have to add the .animated
CSS class in JS for the sidebar.

* DEV: Revert spec change

plugins/chat/spec/system/page_objects/chat/chat_channel.rb

@@ -3,8 +3,6 @@
 module PageObjects
   module Pages
     class ChatChannel < PageObjects::Pages::Base
-      include SystemHelpers
-
       def type_in_composer(input)
         find(".chat-composer-input").send_keys(input)
       end