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_feature/src/lib.rs

@@ -11,7 +11,6 @@
 //! even if it is stabilized or removed, *do not remove it*. Instead, move the
 //! symbol to the `accepted` or `removed` modules respectively.
 
-#![cfg_attr(bootstrap, feature(derive_default_enum))]
 #![feature(once_cell)]
 
 mod accepted;