bug: Emptying all the files in package registry, leaves a model version without a package association

Summary

bug: Emptying all the files in package registry, leaves a model version without a package association

Steps to reproduce

• Create an ML model and a version, adding files into it
• Now go to Deploy/Package registry, and see the package record associated with the above model version
• Delete all files inside the package
• This will delete the entry from packages_packages later,
• and the ml_model_versions will remain without an existing package_id

Possible fixes

• Do not destroy empty ML model packages Do not destroy empty ML model packages in clean... (!166186 - merged)
• Restore a package for failed model versions?