Refactor test to avoid flakiness

This change wraps the expectations in a wait of 60 seconds to
overwrite the default wait timeout of 10 seconds, to avoid false
negative results when system notes take longer to show up when
running tests on CI.

qa/qa/specs/features/ee/browser_ui/2_plan/related_issues/related_issues_spec.rb

@@ -32,15 +32,22 @@ module QA
         issue_1.visit!
 
         Page::Project::Issue::Show.perform do |show|
+          max_wait = 60
+          wait_interval = 1
+
           show.relate_issue(issue_2)
 
-          expect(show).to have_content("marked this issue as related to ##{issue_2.iid}")
-          expect(show.related_issuable_item).to have_content(issue_2.title)
+          show.wait(reload: false, max: max_wait, interval: wait_interval) do
+            expect(show).to have_content("marked this issue as related to ##{issue_2.iid}")
+            expect(show.related_issuable_item).to have_content(issue_2.title)
+          end
 
           show.click_remove_related_issue_button
 
-          expect(show).to have_content("removed the relation with ##{issue_2.iid}")
-          expect(show).not_to have_content(issue_2.title)
+          show.wait(reload: false, max: max_wait, interval: wait_interval) do
+            expect(show).to have_content("removed the relation with ##{issue_2.iid}")
+            expect(show).not_to have_content(issue_2.title)
+          end
         end
       end
     end