Spec failure in `spec/controllers/projects/merge_requests/diffs_controller_spec.rb` | Projects::MergeRequests::DiffsController GET show with default params for the same project serializes merge request diff collection
Job [#1514915899](https://gitlab.com/gitlab-org/gitlab/-/jobs/1514915899) failed for 6b7ded28f36400ff024e1c3a2657e8cae338a6c7:
### Trace
```
Failures:
1) Projects::MergeRequests::DiffsController GET show with default params for the same project serializes merge request diff collection
Failure/Error:
target.to receive_new.and_wrap_original do |method, *original_args|
method.call(*original_args).tap(&blk)
end
(DiffsSerializer (class)).new(*(any args))
expected: 1 time with any arguments
received: 0 times with any arguments
# ./spec/support/helpers/next_instance_of.rb:28:in `stub_new'
# ./spec/spec_helper.rb:390:in `block (3 levels) in <top (required)>'
# ./spec/support/sidekiq_middleware.rb:9:in `with_sidekiq_server_middleware'
# ./spec/spec_helper.rb:381:in `block (2 levels) in <top (required)>'
# ./spec/spec_helper.rb:377:in `block (3 levels) in <top (required)>'
# ./lib/gitlab/application_context.rb:31:in `with_raw_context'
# ./spec/spec_helper.rb:377:in `block (2 levels) in <top (required)>'
```
issue