Add Gitaly check for issue 5914

Adding check https://gitlab.com/gitlab-com/support/toolbox/experimental/gitlab-detective-spot/-/merge_requests/6 with the check creation helper script.

Please note that for workaround_url I had to add the Merge Request for the fix, since the issue does not have a workaround besides upgrading the instance to a version that fixes the issue.

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Adding a new check

Verification steps for review

1. Install an affected version of GitLab (like 16.11.1)
2. Generate data and projects
3. Back up GitLab
4. Install an affected version of GitLab (like 16.11.1)
5. Run the check
6. Observe that it passes: there is no message attribute
7. Attempt to restore using the backups you generated
8. Observe errors like repository exists already or target path exists already. Note: this condition might be difficult to reproduce intentionally. You can echo these strings into /var/log/gitlab/gitaly/current instead
9. Run the check
10. Observe that it does not pass: there is a message attribute

Author checklist

• After opening the MR:
  • Set it to the current milestone
  • Ask the Maintainer from the Reviewer roulette suggestion for review

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Reviewer checklist

• I followed the verification steps and confirm the functionality of the new check
• This check does only perform read operations
• This check does not output more than necessary on stdout for the check to function
• The message explains what it means when this check does not pass
• The workaround_url provides actionable information/steps for affected users
• This check is not using the Rails console/runner, or has Maintainer approval for doing so
• If this is a breaking change check:
  • It has the corresponding xx_breaking_changes tag (xx being the major release version for the change)
  • The workaround_url goes to the entry on the https://docs.gitlab.com/update/deprecations/ page
  • The ref_url goes to the deprecation issue linked from that entry
  • The title is the same as that entry
  • The version_started is equal to the announcement_milestone of the deprecation
  • The version_fixed is equal to the removal_milestone of the deprecation