[Thread] start / initialize Thread service early

We need to do initialization work and start OT daemon when
system_server boots. But the initialize() is called at the phase
PHASE_BOOT_COMPLETED which is too late as Apps (e.g. Google Play
Services) can be started before this phase.

This commit changes to start the Thread service earlier at the phase
PHASE_SYSTEM_SERVICES_READY. Other services such as Wi-Fi, Bluetooth,
Ethernet and Nearby all starts / initializes at this phase.

This commit resolves comment aosp/2737373/comment/d65b9446_8a08117c

Bug: 318787467
Test: atest CtsThreadNetworkTestCases
Change-Id: I7b7b8551b9114cbf07f995b64316c7b420d868b6

thread/service/java/com/android/server/thread/ThreadNetworkService.java

@@ -48,17 +48,20 @@ public class ThreadNetworkService extends IThreadNetworkManager.Stub {
     }
 
     /**
-     * Called by the service initializer.
+     * Called by {@link com.android.server.ConnectivityServiceInitializer}.
      *
      * @see com.android.server.SystemService#onBootPhase
      */
     public void onBootPhase(int phase) {
-        if (phase == SystemService.PHASE_BOOT_COMPLETED) {
+        if (phase == SystemService.PHASE_SYSTEM_SERVICES_READY) {
             mControllerService = ThreadNetworkControllerService.newInstance(mContext);
             mControllerService.initialize();
+        } else if (phase == SystemService.PHASE_BOOT_COMPLETED) {
+            // Country code initialization is delayed to the BOOT_COMPLETED phase because it will
+            // call into Wi-Fi and Telephony service whose country code module is ready after
+            // PHASE_ACTIVITY_MANAGER_READY and PHASE_THIRD_PARTY_APPS_CAN_START
             mCountryCode = ThreadNetworkCountryCode.newInstance(mContext, mControllerService);
             mCountryCode.initialize();
-
             mShellCommand = new ThreadNetworkShellCommand(mCountryCode);
         }
     }