Update new test to use let variables

By using let instead of instance variables we follow what is des-
cribed in our testing best practices.

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

@@ -9,34 +9,38 @@ module QA
         end
       end
 
-      before do
-        Runtime::Browser.visit(:gitlab, Page::Main::Login)
-        Page::Main::Login.perform(&:sign_in_using_credentials)
-
-        @issue_1 = Resource::Issue.fabricate_via_api! do |issue|
+      let(:issue_1) do
+        Resource::Issue.fabricate_via_api! do |issue|
           issue.project = project
           issue.title = 'Issue 1'
         end
+      end
 
-        @issue_2 = Resource::Issue.fabricate_via_api! do |issue|
+      let(:issue_2) do
+        Resource::Issue.fabricate_via_api! do |issue|
           issue.project = project
           issue.title = 'Issue 2'
         end
       end
 
+      before do
+        Runtime::Browser.visit(:gitlab, Page::Main::Login)
+        Page::Main::Login.perform(&:sign_in_using_credentials)
+      end
+
       it 'relates and unrelates one issue to/from another' do
-        @issue_1.visit!
+        issue_1.visit!
 
         Page::Project::Issue::Show.perform do |show|
-          show.relate_issue(@issue_2)
+          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)
+          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.click_remove_issue_button
 
-          expect(show).to have_content("removed the relation with ##{@issue_2.iid}")
-          expect(show).not_to have_content(@issue_2.title)
+          expect(show).to have_content("removed the relation with ##{issue_2.iid}")
+          expect(show).not_to have_content(issue_2.title)
         end
       end
     end