`ValidReferenceConstraintValidator` should use the entity's owner, if applicable, in testing access to reference target

I think the proposed change basically subverts the purpose of ValidReferenceConstraint. It's intended to check whether the current user can access an entity.

This makes no sense outside of form submission, but that's the fault of how we are using it, not of the constraint itself.

Validating that an entity can be accessed by its own owner is not an obvious need to me, and not something I'd particularly expect an entity reference field to do at any time.

I'm sympathetic to the problem - see 📌 Always enforce basefield and entity-level constraints Active for context - but I think it needs to be seen in the bigger picture that our validation system has allowed quite a few bits to develop that only work for form submissions and don't make sense for entities in themselves.

I suggest: works as designed.

Seems there is still discussion to be had. But if carried forward issue summary will need to be updated with proposed solution.

This came up as a daily bugsmash target triage.

Still seems to need discussion on approach and IS update.