Use License Scanning Service in Pipeline page

Why are we doing this work

The backend needs to be changed so that the Licenses tab of the Pipeline page uses the License Scanning Service.

Further details

The Licenses tab of the Pipeline page is handled by PipelinesController#licenses, which uses Pipeline#expose_license_scanning_data?, and SCA::LicenseCompliance.

Proposal

Same as #378085 (closed): Pipeline#license_scanning_report gets a Ci::Reports::LicenseScanning::Report from the LicenseScanningService.

Also, make Pipeline#expose_license_scanning_data? delegate to LicenseScanningService. This could either be a method or a class method – TBD.

Relevant links

The technical evaluation issue doesn't cover this specifically, but it might contain useful information: Spike: Where are License Scanning reports used ... (#377688 - closed)

Non-functional requirements

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

Implementation plan

• Update the pipelines controller so that it uses the license scanning scanner class.
• Remove the deprecated expose_license_scanning_data method now that it is no longer used.
• Remove the ee/lib/gitlab/license_scanning/report.rb file (and associated spec) now that the contained class is no longer used.

Verification steps

1. Set up a project with license scanning e.g. ruby project with dependencies in a Gemfile.lock
2. Run the license scanning job and open the pipeline page
3. Verify that the licenses tab displays the expected licenses for the declared dependencies