[API] Remove unimplemented fields from api_client_authorization
Not used anywhere.
current_api_client_authorization.default_owner_uuid is never set and
current_user.default_owner_uuid doesn't exist.
_id fields are exposed, despite the fact that they are internal database identifiers that are not meaningful to the client. The
owner_uuid field is a virtual field that translates the
user_id to a uuid.
t.add :user_id t.add :api_client_id