[Audit] Repository creation under product creates audit record with empty content
This ticket created for having katello side changes includes audit hook method to repository models.
- Fixes #26675 - audit hook in root_repository model
With this commit, it will show content info instead of
empty value under root_repository's audit record on web-ui.
To achieve this, added audit hook in root_repository so that
it will find associated records like 'content' where no real
association defined on the model.
- Refs #26675 - added test for audit_hook in root_repository