[StatsCompanionService] Updated ShutdownEventReceiver handling

Moved handling to the dedicated worker thread to avoid blocking
System Server main thread

Bug: 325578846
Test: CtsStatsdHostTestCases
Change-Id: I89e65a2fd40533a4eb66cde1b2d3efacbdde3dcd
diff --git a/service/java/com/android/server/stats/StatsCompanionService.java b/service/java/com/android/server/stats/StatsCompanionService.java
index 16e66fe..6e920c5 100644
--- a/service/java/com/android/server/stats/StatsCompanionService.java
+++ b/service/java/com/android/server/stats/StatsCompanionService.java
@@ -755,7 +755,8 @@
             // Setup receiver for device reboots or shutdowns.
             filter = new IntentFilter(Intent.ACTION_REBOOT);
             filter.addAction(Intent.ACTION_SHUTDOWN);
-            mContext.registerReceiverForAllUsers(shutdownEventReceiver, filter, null, null);
+            mContext.registerReceiverForAllUsers(shutdownEventReceiver, filter, null,
+                    /* scheduler= */ mHandler);
 
             // Register listener for statsd_java properties updates.
             DeviceConfig.addOnPropertiesChangedListener(NAMESPACE_STATSD_JAVA,