Use new JSI method to queue microtasks in RuntimeSchedulerTest

Summary:
Changelog: [internal]

Now that `jsi::Runtime::queueMicrotask` is available, we can use it instead of calling an internal Hermes API in `RuntimeSchedulerTest`.

Reviewed By: christophpurrer

Differential Revision: D54416245

fbshipit-source-id: c9cbd3783d9dc1c3df499a7fec7acb6c229ec571

packages/react-native/ReactCommon/react/renderer/runtimescheduler/tests/RuntimeSchedulerTest.cpp

@@ -200,13 +200,7 @@ TEST_P(
           return jsi::Value::undefined();
         });
 
-    // Hermes doesn't expose a C++ API to schedule microtasks, so we just access
-    // the API that it exposes to JS.
-    auto global = runtime_->global();
-    auto enqueueJobFn = global.getPropertyAsObject(*runtime_, "HermesInternal")
-                            .getPropertyAsFunction(*runtime_, "enqueueJob");
-
-    enqueueJobFn.call(*runtime_, std::move(microtaskCallback));
+    runtime_->queueMicrotask(microtaskCallback);
 
     return jsi::Value::undefined();
   });