perf_hooks: avoid memory leak on gc observer

Fixes: nodejs#22229

PR-URL: nodejs#22241
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yang Guo <yangguo@chromium.org>
Reviewed-By: George Adams <george.adams@uk.ibm.com>

src/node_perf.cc

@@ -272,6 +272,9 @@ void MarkGarbageCollectionEnd(Isolate* isolate,
                               v8::GCCallbackFlags flags,
                               void* data) {
   Environment* env = static_cast<Environment*>(data);
+  // If no one is listening to gc performance entries, do not create them.
+  if (!env->performance_state()->observers[NODE_PERFORMANCE_ENTRY_TYPE_GC])
+    return;
   GCPerformanceEntry* entry =
       new GCPerformanceEntry(env,
                              static_cast<PerformanceGCKind>(type),