Make the 'issuables list meta-data' shared example less dangerous

This shared example would take an object's database ID and create a
number of objects based on it. If for some reason the ID were a high
number, like 20, this would create `20 + 21 + 22` objects.

Not only was this dangerous from a performance perspective, it was
entirely unnecessary, as the behavior it was testing is already
well-tested in the unit test for the underlying object. For a controller
test, which is what's including this shared example, all we need to do
is verify that the assigned object contains the correct `id => object`
Hash, which is what we now test for.

spec/controllers/projects/merge_requests_controller_spec.rb

@@ -106,7 +106,7 @@ describe Projects::MergeRequestsController do
   end
 
   describe 'GET index' do
-    let!(:merge_request) { create(:merge_request_with_diffs, target_project: project, source_project: project) }
+    let(:merge_request) { create(:merge_request_with_diffs, target_project: project, source_project: project) }
 
     def get_merge_requests(page = nil)
       get :index,
@@ -150,6 +150,8 @@ describe Projects::MergeRequestsController do
     context 'when filtering by opened state' do
       context 'with opened merge requests' do
         it 'lists those merge requests' do
+          expect(merge_request).to be_persisted
+
           get_merge_requests
 
           expect(assigns(:merge_requests)).to include(merge_request)

spec/support/issuables_list_metadata_shared_examples.rb

@@ -11,10 +11,6 @@ shared_examples 'issuables list meta-data' do |issuable_type, action = nil|
         end
 
       @issuable_ids << issuable.id
-
-      issuable.id.times       { create(:note, noteable: issuable, project: issuable.project) }
-      (issuable.id + 1).times { create(:award_emoji, :downvote, awardable: issuable) }
-      (issuable.id + 2).times { create(:award_emoji, :upvote, awardable: issuable) }
     end
   end
 
@@ -27,10 +23,9 @@ shared_examples 'issuables list meta-data' do |issuable_type, action = nil|
 
     meta_data = assigns(:issuable_meta_data)
 
-    @issuable_ids.each do |id|
-      expect(meta_data[id].notes_count).to eq(id)
-      expect(meta_data[id].downvotes).to eq(id + 1)
-      expect(meta_data[id].upvotes).to eq(id + 2)
+    aggregate_failures do
+      expect(meta_data.keys).to match_array(@issuable_ids)
+      expect(meta_data.values).to all(be_kind_of(Issuable::IssuableMeta))
     end
   end