Auto merge of #76244 - vandenheuvel:remove__paramenv__def_id, r=nikomatsakis

Removing the `def_id` field from hot `ParamEnv` to make it smaller

This PR addresses https://github.com/rust-lang/rust/issues/74865.

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -593,6 +593,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     }
                 }
             }
+            ty::PredicateAtom::TypeWellFormedFromEnv(..) => {
+                bug!("TypeWellFormedFromEnv is only used for chalk")
+            }
         }
     }