Auto merge of #100237 - cjgillot:no-special-hash-hir, r=nagisa

Remove manual implementations of HashStable for hir::Expr and hir::Ty.

We do not need to force hashing HIR bodies inside those nodes. The contents of bodies are not accessible from the `hir_owner` query which used `hash_without_bodies`. When the content of a body is required, the access is still done using `hir_owner_nodes`, which continues hashing HIR bodies.

Author: bors