Rollup merge of #105537 - kadiwa4:remove_some_imports, r=fee1-dead

compiler: remove unnecessary imports and qualified paths

Some of these imports were necessary before Edition 2021, others were already in the prelude.

I hope it's fine that this PR is so spread-out across files :/

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -30,7 +30,6 @@ mod test;
 mod util;
 
 use std::borrow::Borrow;
-use std::convert::TryFrom;
 use std::mem;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {

compiler/rustc_mir_build/src/build/matches/util.rs

@@ -7,7 +7,6 @@ use rustc_middle::thir::*;
 use rustc_middle::ty;
 use rustc_middle::ty::TypeVisitable;
 use smallvec::SmallVec;
-use std::convert::TryInto;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub(crate) fn field_match_pairs<'pat>(

compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs

@@ -45,7 +45,7 @@
 use std::cell::Cell;
 use std::cmp::{self, max, min, Ordering};
 use std::fmt;
-use std::iter::{once, IntoIterator};
+use std::iter::once;
 use std::ops::RangeInclusive;
 
 use smallvec::{smallvec, SmallVec};