Auto merge of #100812 - Nilstrieb:revert-let-chains-nightly, r=Mark-Simulacrum

Revert let_chains stabilization

This is the revert against master, the beta revert was already done in #100538.

Bumps the stage0 compiler which already has it reverted.

compiler/rustc_borrowck/src/lib.rs

@@ -2,6 +2,7 @@
 
 #![allow(rustc::potential_query_instability)]
 #![feature(box_patterns)]
+#![feature(let_chains)]
 #![feature(let_else)]
 #![feature(min_specialization)]
 #![feature(never_type)]