Set loop_interval to 0 in ApplicationLoop benchmark to skip sleep

tests/benchmarks/core/bench_application_loop.cpp

@@ -10,6 +10,9 @@ namespace esphome::benchmarks {
 // This measures the baseline overhead of the main loop: scheduler,
 // timing, before/after loop tasks, and yield_with_select_.
 static void ApplicationLoop_Empty(benchmark::State &state) {
+  // Set loop interval to 0 so yield_with_select_ returns immediately
+  // instead of sleeping. This benchmarks the loop overhead, not the sleep.
+  App.set_loop_interval(0);
   for (auto _ : state) {
     App.loop();
   }