This is cropping up all over the place. After a brief dive, I'm really
not sure why we have `arel.bind_values` at all. A cursory grep didn't
reveal where they're actually being assigned (it's definitely in AR, not
in Arel). I'd like to dig further into it, as I'm fairly certain we
don't actually need it, we just need a way for the predicate builder to
communicate merged binds upstream.

Fixes #18414