Remove the license_scanning artifact report type

Why are we doing this work

The license_scanning artifact report type is deprecated as of GitLab 16.9.

This issue is to remove the corresponding codebase in the rails backend and no longer accept this type as a valid keyword in the CI configuration

Relevant links

#439301 (closed)

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

Verification steps