Finish bumping stage0

It looks like the last time had left some remaining cfg's -- which made me think
that the stage0 bump was actually successful. This brings us to a released 1.62
beta though.

compiler/rustc_infer/src/lib.rs

@@ -16,7 +16,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(box_patterns)]
 #![feature(control_flow_enum)]
-#![cfg_attr(bootstrap, feature(derive_default_enum))]
 #![feature(extend_one)]
 #![feature(label_break_value)]
 #![feature(let_chains)]