Auto merge of #152636 - nnethercote:big-cleanups, r=Zalathar

Big query system cleanups

Recent PRs have moved a lot of code from `rustc_query_system` to `rustc_middle` and `rustc_query_impl`, where this code now has access to `TyCtxt`, e.g. rust-lang/rust#152419, rust-lang/rust#152516. As a result, a lot of abstraction and indirection that existed to work around this limitation is no longer necessary. This PR removes a lot of it.

r? @Zalathar

Author: bors