If an attribute has more permissive security rules than the entity
type itself, we should be green and not deny action because of an
early global entity permission check (with the more restrictive
rules).

Only if one attribute with the entity-level permission rules is edited
will the global check be performed.

Note:

* the "if action == 'delete'" check at the entry of
  check_entity_attributes is a guard for a condition currently not
  happening in cubicweb itself (but application hooks could
  conceivably call this function with a 'delete' action)

Closes #3489895.