New Feature Request: support images version history clean

### Background

The upgrade of image versions is very frequent. As new versions such as v1.2.3 are used, old version images (e.g., v0.0.1, v1.0.0, v1.2.0) will no longer be used, but they are still occupying r2 storage space.

### Requirements

Old version images need to be cleaned up to save space.
Support cleanup policies, such as triggering at regular intervals or when updating to a new version.

Cleanup policies can include:

- Retain the most recent x versions

No files, tests, or entry points are named. Review how image versions are stored in the Workers and R2-backed registry, then define the cleanup policy and its trigger points; done should include retaining the most recent x versions while removing older images and freeing storage.

Written by the indexing model from the issue text.