Update click_vulnerability test function

The Vulnerability modal was transitioned to GlModal
update the function to click vulnerability
such that test failures are addressed

qa/qa/ee/page/merge_request/show.rb

@@ -128,7 +128,7 @@ module QA
             end
 
             wait_until(reload: false) do
-              find_element(:vulnerability_modal_content)[:class].include? 'show'
+              find_element(:vulnerability_modal_content)
             end
           end