Rollup merge of #126776 - nnethercote:rustfmt-use-pre-cleanups-2, r=cuviper

Clean up more comments near use declarations

#125443 will reformat all use declarations in the repository. There are a few edge cases involving comments on use declarations that require care. This PR fixes them up so #125443 can go ahead with a simple `x fmt --all`. A follow-up to #126717.

r? ``@cuviper``

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -34,7 +34,6 @@ use super::{
     Pointer, Projectable, Scalar, ValueVisitor,
 };
 
-// for the validation errors
 use super::InterpError::UndefinedBehavior as Ub;
 use super::InterpError::Unsupported as Unsup;
 use super::UndefinedBehaviorInfo::*;