Fix non-nullable engineName for code quality degradations

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/138752



Merged-by: Heinrich Lee Yu <heinrich@gitlab.com>
Approved-by: Adam Hegyi <ahegyi@gitlab.com>
Approved-by: Heinrich Lee Yu <heinrich@gitlab.com>
Co-authored-by: Ahmed Hemdan <ahemdan@gitlab.com>