Don't try to delete nonexistent group

If the test is in quarantine it won't create a group, so it should
not try to delete the group in the after hook.

qa/qa/specs/features/browser_ui/1_manage/ee_group/group_saml_sso_spec.rb

@@ -104,8 +104,9 @@ module QA
           end
         end
       end
+
       after(:all) do
-        remove_group(@group)
+        remove_group(@group) unless @group.nil?
       end
     end