Update "Duo Pro" add-on UI references to "GitLab Duo Pro"

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/144461



Merged-by: Himanshu Kapoor <info@fleon.org>
Approved-by: Martin Čavoj <mcavoj@gitlab.com>
Approved-by: Aaron Huntsman <ahuntsman@gitlab.com>
Approved-by: Himanshu Kapoor <info@fleon.org>
Approved-by: Dmytro Biryukov <dbiryukov@gitlab.com>
Reviewed-by: Martin Čavoj <mcavoj@gitlab.com>
Co-authored-by: Mohamed Moustafa <mmoustafa@gitlab.com>