Transient order-dependent failure in spec/features/merge_request/user_merges_when_pipeline_succeeds_spec.rb

This failure first appeared in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6321 (https://gitlab.com/gitlab-org/gitlab-ee/-/jobs/78354802) and was determined to be order-dependent and unrelated to those changes.

rspec --bisect reduced the reproduction to:

rspec './spec/features/merge_request/user_merges_when_pipeline_succeeds_spec.rb[1:1:1:4:1:1,1:1:2:1]' --order defined

The test is exactly the same in CE but wasn't able to be reproduced there.