Remove old OCI artifacts from old versions under old namespace

We have the following OCI packages in ghcr.io:
https://github.com/kubewarden/hostpaths-psp-policy/pkgs/container/policies%2Fpsp-hostpaths

These are under ` ghcr.io/kubewarden/policies/psp-hostpaths` instead of `ghcr.io/kubewarden/policies/hostpaths-psp`, and are untouched since almost 4 years. Given that the policy version is now `v1.X`, maybe it is time to remove them.