Publish official Docker images when PUBLISH_IMAGES is set

What does this MR do?

In a pipeline for the default branch, and when CI variable PUBLISH_IMAGES is set, tag and push Docker images with image tags that match:

• the patch version X.Y.Z
• the major version X

This is a port of gitlab-org/security-products/ci-templates!255 (merged) and gitlab-org/security-products/ci-templates!257 (merged)

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab/-/issues/338826

Does this MR meet the acceptance criteria?

• [-] Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Job definition example
  • CI Templates (to be removed)
  • Vendored CI Templates (also in CE)
  • Ensure that all of the ENV vars supported are propagated to Docker containers upon docker run in job definitions
• Conforms to the code review guidelines
• Security reports checked/validated by reviewer