heap: Explicitly clear moved-away struct

This struct is reused across various GC cycles. In the way that it's
used here, std::move does not clear the vector of events.

Change-Id: I21e3f74e3ce13fad063499bed19c287902cb90cf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3460408Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Nikolaos Papaspyrou <nikolaos@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79078}

src/heap/gc-tracer.cc

@@ -1441,6 +1441,7 @@ void FlushBatchedIncrementalEvents(
   DCHECK(!batched_events.events.empty());
   isolate->metrics_recorder()->AddMainThreadEvent(std::move(batched_events),
                                                   GetContextId(isolate));
+  batched_events = {};
 }
 
 }  // namespace
@@ -1455,7 +1456,7 @@ void GCTracer::ReportFullCycleToRecorder() {
       heap_->isolate()->metrics_recorder();
   DCHECK_NOT_NULL(recorder);
   if (!recorder->HasEmbedderRecorder()) {
-    incremental_mark_batched_events_.events.clear();
+    incremental_mark_batched_events_ = {};
     if (cpp_heap) {
       cpp_heap->GetMetricRecorder()->ClearCachedEvents();
     }