Revert "Use Predicate ConstraintCategory when normalizing"

This reverts commit aae37f8763.

compiler/rustc_trait_selection/src/traits/query/normalize.rs

@@ -48,11 +48,10 @@ impl<'cx, 'tcx> AtExt<'tcx> for At<'cx, 'tcx> {
         T: TypeFoldable<'tcx>,
     {
         debug!(
-            "normalize::<{}>(value={:?}, param_env={:?}, cause={:?})",
+            "normalize::<{}>(value={:?}, param_env={:?})",
             std::any::type_name::<T>(),
             value,
             self.param_env,
-            self.cause,
         );
         if !needs_normalization(&value, self.param_env.reveal()) {
             return Ok(Normalized { value, obligations: vec![] });