Update clair executable to v12

Problem to solve

clair executable v12 is available, we should consider upgrading our template.

Proposal

• review the changelog
• update the CLAIR_EXECUTABLE_VERSION variable in https://gitlab.com/gitlab-org/gitlab-ee/blob/master/lib/gitlab/ci/templates/Security/Container-Scanning.gitlab-ci.yml

Testing

• Check relevant test projects leveraging Container-Scanning and make sure QA pipelines are passing with this new version: QA projects for Container Scanning

What does success look like, and how can we measure that?

Our feature is leveraging the latest version (v12) of Clair executable

What is the type of buyer?

GitLab Ultimate

Links / references