Remove line instead of just commenting out

Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de>

Author: Lireer

src/test/ui/consts/promotion.rs

@@ -4,7 +4,6 @@
 //[opt_with_overflow_checks]compile-flags: -C overflow-checks=on -O
 
 // build-pass
-// #![allow(arithmetic_overflow, unconditional_panic)]
 
 const fn assert_static<T>(_: &'static T) {}