GitalyClient spec: Remove the diff between CE/EE

What does this MR do?

Port a non EE specific test back to CE, by running curl -sSl https://gitlab.com/gitlab-org/gitlab-ee/raw/master/spec/lib/gitlab/gitaly_client/ref_service_spec.rb > spec/lib/gitlab/gitaly_client/ref_service_spec.rb

What are the relevant issue numbers?

Couldn't find them so far, might be one.

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• [-] Documentation created/updated via this MR
• [-] Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• [-] Tested in all supported browsers
• [-] Conforms to the code review guidelines
  • Well, Tiago wrote the original test, so it has to
• [-] Conforms to the merge request performance guidelines
• [-] Conforms to the style guides
• [-] Conforms to the database guides
• [-] Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer