Noop for test GC pass when not in debug

To get accurate metrics when load testing an optimized build, the GC pass
that is normally done per test is now disabled.

src/workerd/io/worker-entrypoint.c++

@@ -513,6 +513,7 @@ kj::Promise<WorkerInterface::CustomEvent::Result>
 template <typename T>
 void WorkerEntrypoint::maybeAddGcPassForTest(
     IoContext& context, kj::Promise<T>& promise) {
+#ifdef KJ_DEBUG
   if (isPredictableModeForTest()) {
     auto worker = kj::atomicAddRef(context.getWorker());
     if constexpr (kj::isSameType<T, void>()) {
@@ -530,6 +531,7 @@ void WorkerEntrypoint::maybeAddGcPassForTest(
       });
     }
   }
+#endif
 }
 
 } // namespace workerd