Avoid using expect_any_instance_of

We can't use it for prepended module, so use
`and_wrap_original` to wrap around the instance.

spec/workers/update_merge_requests_worker_spec.rb

@@ -18,8 +18,13 @@ describe UpdateMergeRequestsWorker do
     end
 
     it 'executes MergeRequests::RefreshService with expected values' do
-      expect(MergeRequests::RefreshService).to receive(:new).with(project, user).and_call_original
-      expect_any_instance_of(MergeRequests::RefreshService).to receive(:execute).with(oldrev, newrev, ref)
+      expect(MergeRequests::RefreshService).to receive(:new)
+        .with(project, user).and_wrap_original do |method, *args|
+          method.call(*args).tap do |refresh_service|
+            expect(refresh_service)
+              .to receive(:execute).with(oldrev, newrev, ref)
+          end
+        end
 
       perform
     end