ci-package-builder: Hardcode the license blacklist

Rather than relying on variables set up at the subgroup level on GitLab, hardcode the license blacklist in the definition.

This has two benefits:

• changes to the list of blocked licenses are tracked in git
• licensing checks are still applied on packages in non-standard locations such as when forking them
• it gets rid of something that prevents us from moving to a flatter hierarchy where all the packages are directly under pkg/