refactor: remove dead utils/bench.rs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/ahfail-gtklock/src/utils/bench.rs

@@ -1,12 +0,0 @@
-use std::time::Instant;
-
-pub fn time_execution<F, T>(name: &str, f: F) -> T
-where
-    F: FnOnce() -> T,
-{
-    let start = Instant::now();
-    let result = f();
-    let duration = start.elapsed();
-    println!("[benchmark] {}: {:?}", name, duration);
-    result
-}