Show count of facet values always, not just for `?_facet_size=max`

> You've caused me to rethink this feature - I no longer think there's value in only showing these numbers if `?_facet_size=max` as opposed to all of the time.

_Originally posted by @simonw in https://github.com/simonw/datasette/issues/1423#issuecomment-995023410_