Remove Drop-caused migration-added captures

All of these were added due to insignificant Drop types being present.

compiler/rustc_typeck/src/check/compare_method.rs

@@ -1192,7 +1192,6 @@ fn compare_type_predicate_entailment<'tcx>(
         normalize_cause.clone(),
     );
     tcx.infer_ctxt().enter(|infcx| {
-        let _ = &impl_ty_own_bounds;
         let inh = Inherited::new(infcx, impl_ty.def_id.expect_local());
         let infcx = &inh.infcx;
 

compiler/rustc_typeck/src/check/method/probe.rs

@@ -441,7 +441,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // this creates one big transaction so that all type variables etc
         // that we create during the probe process are removed later
         self.probe(|_| {
-            let _ = &steps;
             let mut probe_cx = ProbeContext::new(
                 self,
                 span,