Release Container Scanning v6

Proposal

Similar to Release Gemnasium v4 (#408528 - closed), we need to release a new version of container-scanning to coincide with the new major release 16.0 of GitLab

Implementation Plan

Steps to Release Container Scanning v6.

1. Create v6.x branch from master
2. Implement Remove deprecated Container Scanning variables ... (#371840 - closed) with a target of v6.x
3. Create v5.x branch from master and make it protected
4. Release 6.0.0 tag to publish registry.gitlab.com/security-products/container-scanning:6
5. Verified that a CS scan with container-scanning:6, container-scanning/trivy:6, container-scanning/grpe:6 works
6. Update gitlab monolith
   • Update CS_ANALYZER_IMAGE to "$CI_TEMPLATE_REGISTRY_HOST/security-products/container-scanning:6" in CI template.
     • Upgrade Container Scanning analyzer to version 6 (!118947 - merged)
   • Update user documentation
     • Upgrade Container Scanning analyzer to version 6 (!118947 - merged)
   • Update references to Docker images.
     • Upgrade Container Scanning analyzer to version 6 (!118947 - merged)
   • Monitor that Upgrade Container Scanning analyzer to version 6 (!118947 - merged) is merged
7. Merge v6.x into master.
8. Update trigger-db-update scheduled pipeline TRIGGER_DB_UPDATE_FOR_MAJOR_VERSIONS variable to either 4,5,6 or 5,6. Depends on this thread

Verification steps

On GitLab 16.x, run a new pipeline in a project where the Container Scanning CI template is included.

• ensure the container scanning job successfully runs the container-scanning:6 image.