Allow Duo Workflow Service to run from AI Gateway repo

Closes #2574

See merge request !4773



Merged-by: Tiger Watson <twatson@gitlab.com>
Approved-by: Jeff Park <jpark@gitlab.com>
Approved-by: Tiger Watson <twatson@gitlab.com>
Reviewed-by: Tiger Watson <twatson@gitlab.com>
Co-authored-by: Shinya Maeda <shinya@gitlab.com>