Flaky integration test in `spec/controllers/projects/merge_requests/diffs_controller_spec.rb` | Projects::MergeRequests::DiffsController GET show behaves like cached diff collection ensures diff highlighting cache writing

Job #929049278 failed for gitlab-org/security/gitlab@585f88b427ef3896c5720ea6e67e09256c551fc3:

Trace

Failures:
  1) Projects::MergeRequests::DiffsController GET show behaves like cached diff collection ensures diff highlighting cache writing
     Failure/Error:
       target.to receive_new.and_wrap_original do |method, *original_args|
         method.call(*original_args).tap(&blk)
       end
       (Gitlab::Diff::HighlightCache (class)).new(*(any args))
           expected: 1 time with any arguments
           received: 0 times with any arguments