Fix eslint - UserCallout reference

What does this MR do?

Fix eslint. UserCallout reference needs to be removed as it is not being used anymore

Are there points in the code the reviewer needs to double check?

None

Why was this MR needed?

Eslint was failing on master after UserCallout was removed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16608/diffs#dc2de5a9f57ef8263663b3130fd53e8f3821a552_603_597 with an out of date master.

We would need the merge-train to automatically detect this, https://gitlab.com/gitlab-org/gitlab-ee/issues/3709

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Closes #42298 (closed)