Remove code for 'license_management'

We renamed License Management to License Compliance (see &659 (closed)).

This issue is to remove old code handling license_management support. This also includes removing license_management licensed feature and License-Management.gitlab-ci.yml CI template.

We should wait at least until GitLab 13.0 before doing this.

Implementation plan

• Drop support for license_management artifact #216995 (closed)
• Drop support for License-Management CI template #213572 (closed)
• Remove license_management licensed feature #213574 (closed)
• Switch AutoDev-Ops template to use License-Scanning #213572 (closed)

Follow-ups

• Migrate license_management artifacts to license_scanning #213571 (closed) (should be done after we drop support for license_management artifacts)
• Update License Compliance analyzer to generate gl-license-scanning-report file #213577 (closed) (should be done after we drop support for CI template for License Management)