Remove duplicate scope present in user.rb

What does this MR do?

Remove duplicate scope present in user.rb - https://gitlab.com/gitlab-org/gitlab/blob/247eeb3219850a5638157adb2fa6ece3adfc2bd9/app/models/user.rb#L107

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers