Auto merge of #107241 - clubby789:bootstrap-lto-off, r=simulacrum

Add `rust.lto=off` to bootstrap and set as compiler/library default

Closes #107202

The issue mentions `embed-bitcode=on`, but here https://github.com/rust-lang/rust/blob/c8e6a9e8b6251bbc8276cb78cabe1998deecbed7/src/bootstrap/compile.rs#L379-L381
it appears that this is always set for std stage 1+, so I'm unsure if changes are needed here.

`@rustbot` label +A-bootstrap

Author: bors