Ensure UserAddOnAssignmentVersion audits are created also through associations deletions

Problem

During the issue Capture deletes in subscription_user_add_on_ass... (#508335 - closed) we discovered the following: When we delete associations, for example, users or namespaces, UserAddOnAssignment entities are deleted, but we don't create an audit via Papertrail for those entities.

Proposal

Ensure that audits for UserAddOnAssignments are created when an association, for example, user or namespace, gets deleted.