Remove background thread from callback bench

benchmarks/bench_metric.cpp

@@ -176,29 +176,13 @@ int main() {
       return gauge_value.load(std::memory_order_relaxed);
     });
 
-    // Background thread updating callback values
-    std::atomic<bool> stop_callback{false};
-    std::latch start_latch{2}; // Background thread + benchmark thread
-
-    std::thread callback_updater([&]() {
-      start_latch.arrive_and_wait(); // Wait for benchmark to start
-      while (!stop_callback.load()) {
-        counter_value.fetch_add(1);
-        gauge_value.store(gauge_value.load() + 1);
-      }
-    });
-
     ArenaAllocator arena;
 
-    start_latch.arrive_and_wait(); // Wait for background thread to be ready
     bench.run("render() - with callback metrics", [&]() {
       auto output = metric::render(arena);
       ankerl::nanobench::doNotOptimizeAway(output);
       arena.reset();
     });
-
-    stop_callback.store(true);
-    callback_updater.join();
   }
 
   // Render performance scaling