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_codegen_ssa/src/base.rs

@@ -41,7 +41,6 @@ use rustc_span::{DebuggerVisualizerFile, DebuggerVisualizerType};
 use rustc_target::abi::{Align, Size, VariantIdx};
 
 use std::collections::BTreeSet;
-use std::convert::TryFrom;
 use std::time::{Duration, Instant};
 
 use itertools::Itertools;