Add missing feature flag to mr notes spec

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

spec/features/notes_on_merge_requests_spec.rb

@@ -132,7 +132,7 @@ describe "On a merge request", js: true, feature: true do
   end
 end
-describe "On a merge request diff", js: true do
+describe "On a merge request diff", js: true, feature: true do
   let(:merge_request) { create(:merge_request, :with_diffs, :simple) }
   let(:project) { merge_request.source_project }
@@ -210,9 +210,3 @@ describe "On a merge request diff", js: true do
     end
   end
 end
-
-describe "On merge request discussion", js: true do
-  describe "with merge request diff note"
-  describe "with commit note"
-  describe "with commit diff note"
-end