That ability was introduced at #11898 as `Relation#update` without
giving ids, so the ability on the class level is not documented and not
tested.

c83e30da which fixes #33470 has lost two undocumented abilities.

One has fixed at 5c656889, but I missed the ability on the class level.

Removing any feature should not be suddenly happened in a stable version
even if that is not documented.

I've restored the ability and added test case to avoid any regression in
the future.

Fixes #34743.