Replace edge with latest

What does this MR do?

1. Stops publishing the edge tag for CS images.
2. Replaces latest with the definition of edge.

This creates a more stable tag for latest. At the moment, it can contain any major supported version. Currently, this means latest could run CS version 5, 6 or 7.

Another benefit is to stabilize vulnerability management for the project. With the introduction of CS for container registry, we'll trigger a CS scan every time the latest tag is published. With this change, we ensure that the vulnerability report is always reflecting the default branch.

What are the relevant issue numbers?

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
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer