Add admin issue check to create epic issue link

ee/app/services/epic_issues/create_service.rb

@@ -45,6 +45,7 @@ module EpicIssues
 
     def linkable_issue?(issue)
       issue.supports_epic? &&
+        can?(current_user, :admin_issue, issue.project) &&
         issuable_group_descendants.include?(issue.project.group) &&
         !previous_related_issuables.include?(issue)
     end

ee/spec/services/epic_issues/create_service_spec.rb

@@ -160,9 +160,10 @@ RSpec.describe EpicIssues::CreateService do
               # threshold 24 because 6 queries are generated for each insert
               # (savepoint, find, exists, relative_position get, insert, release savepoint)
               # and we insert 5 issues instead of 1 which we do for control count
+              # plus 4 to include additional authorization queries "SELECT MAX("project_authorizations"."access_level")"
               expect { described_class.new(epic, user, params).execute }
                 .not_to exceed_query_limit(control_count)
-                .with_threshold(29)
+                .with_threshold(33)
             end
           end
 
@@ -179,6 +180,10 @@ RSpec.describe EpicIssues::CreateService do
 
             subject { assign_issue([Gitlab::Routing.url_helpers.namespace_project_issue_url(namespace_id: issue.project.namespace, project_id: issue.project, id: issue.iid)])}
 
+            before do
+              project2.add_reporter(user)
+            end
+
             include_examples 'returns success'
           end
 
@@ -202,6 +207,7 @@ RSpec.describe EpicIssues::CreateService do
 
               expect(created_link2.relative_position).to be < created_link1.relative_position
             end
+
             it 'orders the epic issues to the first place and moves the existing ones down' do
               existing_link = create(:epic_issue, epic: epic, issue: issue3)