Remove let_chains feature gate from even more tests

Author: est31

tests/mir-opt/building/logical_or_in_conditional.rs

@@ -1,6 +1,6 @@
 // skip-filecheck
 //@ compile-flags: -Z validate-mir
-#![feature(let_chains)]
+//@ edition: 2024
 struct Droppy(u8);
 impl Drop for Droppy {
     fn drop(&mut self) {

tests/ui/deriving/auxiliary/malicious-macro.rs

@@ -1,4 +1,4 @@
-#![feature(let_chains)]
+//@ edition: 2024
 
 extern crate proc_macro;
 

tests/ui/drop/drop-order-comparisons.e2021.fixed

@@ -24,7 +24,7 @@
 //@ [e2024] edition: 2024
 //@ run-pass
 
-#![feature(let_chains)]
+#![cfg_attr(e2021, feature(let_chains))]
 #![cfg_attr(e2021, warn(rust_2024_compatibility))]
 
 fn t_bindings() {

tests/ui/drop/drop-order-comparisons.rs

@@ -24,7 +24,7 @@
 //@ [e2024] edition: 2024
 //@ run-pass
 
-#![feature(let_chains)]
+#![cfg_attr(e2021, feature(let_chains))]
 #![cfg_attr(e2021, warn(rust_2024_compatibility))]
 
 fn t_bindings() {

tests/ui/lint/issue-121070-let-range.rs

@@ -1,6 +1,6 @@
 //@ check-pass
+//@ edition:2024
 
-#![feature(let_chains)]
 #![allow(irrefutable_let_patterns)]
 fn main() {
     let _a = 0..1;

tests/ui/mir/issue-99852.rs

@@ -1,6 +1,6 @@
 //@ check-pass
 //@ compile-flags: -Z validate-mir
-#![feature(let_chains)]
+//@ edition: 2024
 
 fn lambda<T, U>() -> U
 where

tests/ui/parser/brace-in-let-chain.rs

@@ -1,6 +1,6 @@
 // issue #117766
+//@ edition: 2024
 
-#![feature(let_chains)]
 fn main() {
     if let () = ()
         && let () = () {

tests/ui/parser/deli-ident-issue-1.rs

@@ -1,4 +1,4 @@
-#![feature(let_chains)]
+//@ edition: 2024
 trait Demo {}
 
 impl dyn Demo {

tests/ui/parser/issues/issue-103381.fixed

@@ -1,6 +1,6 @@
+//@ edition: 2024
 //@ run-rustfix
 
-#![feature(let_chains)]
 #![allow(unused_variables)]
 #![allow(dead_code)]
 #![allow(irrefutable_let_patterns)]

tests/ui/parser/issues/issue-103381.rs

@@ -1,6 +1,6 @@
+//@ edition: 2024
 //@ run-rustfix
 
-#![feature(let_chains)]
 #![allow(unused_variables)]
 #![allow(dead_code)]
 #![allow(irrefutable_let_patterns)]