Remove wait_for_loading duplicate method

We now have wait_for_requests which serves the same
purpose as wait_for_loading

qa/qa/page/component/note.rb

@@ -162,10 +162,6 @@ module QA
           fill_element :reply_field, reply_text
         end
 
-        def wait_for_loading
-          has_no_element?(:skeleton_note_placeholer)
-        end
-
         private
 
         def select_filter_with_text(text)
@@ -174,7 +170,7 @@ module QA
             click_element :discussion_filter_dropdown
             find_element(:filter_menu_item, text: text).click
 
-            wait_for_loading
+            wait_for_requests
           end
         end
       end

qa/qa/page/merge_request/show.rb

@@ -162,15 +162,12 @@ module QA
         def click_discussions_tab
           click_element(:notes_tab)
 
-          wait_for_loading
+          wait_for_requests
         end
 
         def click_diffs_tab
           click_element(:diffs_tab)
-
-          wait_for_loading
-
-          click_element(:dismiss_popover_button) if has_element?(:dismiss_popover_button)
+          click_element(:dismiss_popover_button) if has_element?(:dismiss_popover_button, wait: 1)
         end
 
         def click_pipeline_link