Add wait to e2e assignee check

qa/qa/page/component/issuable/sidebar.rb

@@ -65,9 +65,11 @@ module QA
 
           def has_assignee?(username)
             within_element(:assignee_block) do
+              wait_until(reload: false) do
                 has_text?(username)
               end
             end
+          end
 
           def has_no_assignee_named?(username)
             within_element(:assignee_block) do