Merge branch 'jnutt/rename-trait' into 'master'

Rename Import::SourceUser trait

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/160704



Merged-by: Mikołaj Wawrzyniak <mwawrzyniak@gitlab.com>
Approved-by: Mikołaj Wawrzyniak <mwawrzyniak@gitlab.com>
Co-authored-by: James Nutt <jnutt@gitlab.com>