Remove in_band_lifetimes from rustc_mir_transform

This one is a heavy `'tcx` user.

Two interesting ones:

This one had the `'tcx` declared on the function, despite the trait taking a `'tcx`:
```diff
-impl Visitor<'_> for UsedLocals {
+impl<'tcx> Visitor<'tcx> for UsedLocals {
     fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
```

This one use in-band for one, and underscore for the other:
```diff
-pub fn remove_dead_blocks(tcx: TyCtxt<'tcx>, body: &mut Body<'_>) {
+pub fn remove_dead_blocks<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
```

compiler/rustc_mir_transform/src/remove_uninit_drops.rs

@@ -86,7 +86,7 @@ impl<'tcx> MirPass<'tcx> for RemoveUninitDrops {
     }
 }
 
-fn is_needs_drop_and_init(
+fn is_needs_drop_and_init<'tcx>(
     tcx: TyCtxt<'tcx>,
     param_env: ParamEnv<'tcx>,
     maybe_inits: &BitSet<MovePathIndex>,
@@ -158,7 +158,7 @@ fn is_needs_drop_and_init(
     }
 }
 
-fn variant_needs_drop(
+fn variant_needs_drop<'tcx>(
     tcx: TyCtxt<'tcx>,
     param_env: ParamEnv<'tcx>,
     substs: SubstsRef<'tcx>,