remove periodically older images from GHCR to save space

## Summary
Due to storage limits of GHCR older docker images of client and server should be erased regularly. Latest and at least 3 previous images for client and server should always be accessible.

**Probably this issue is redundant as public repos seem to have no limits on GHCR usage:** https://docs.github.com/en/packages/learn-github-packages/introduction-to-github-packages#about-billing-for-github-packages

## [Acceptance criteria](https://www.atlassian.com/work-management/project-management/acceptance-criteria)
- [ ] GHCR always stores at least 3 versions back from current deployed version of client and server
- [ ] old packages on GHCR are removed regularly fully automatically

## Notes
important context