Collect cpu/mem stats via VmExited atom

Bug: 257159905
Test: atest MicrodroidHostTests#testTelemetryPushedAtoms

Change-Id: I156bdc0f30e89ce28c75f8d360959d2660957c01
diff --git a/virtualizationservice/src/aidl.rs b/virtualizationservice/src/aidl.rs
index bc697e3..00a46bf 100644
--- a/virtualizationservice/src/aidl.rs
+++ b/virtualizationservice/src/aidl.rs
@@ -1075,8 +1075,8 @@
             let stream = vm.stream.lock().unwrap().take();
             vm.callbacks.notify_payload_started(cid, stream);
 
-            let vm_start_timestamp = vm.vm_start_timestamp.lock().unwrap();
-            write_vm_booted_stats(vm.requester_uid as i32, &vm.name, *vm_start_timestamp);
+            let vm_start_timestamp = vm.vm_metric.lock().unwrap().start_timestamp;
+            write_vm_booted_stats(vm.requester_uid as i32, &vm.name, vm_start_timestamp);
             Ok(())
         } else {
             error!("notifyPayloadStarted is called from an unknown CID {}", cid);