Read SystemConfig on a worker thread

Also added lazy accessor for mBackgroundLaunchBroadcasts to give more
time for SystemConfig init to finish.

Test: manual
Bug: 34809967
Change-Id: Iaba0ac61714d94e72d571f33cd22d8700b89bb31
diff --git a/services/core/java/com/android/server/SystemServerInitThreadPool.java b/services/core/java/com/android/server/SystemServerInitThreadPool.java
index d196850..5cc9bfd 100644
--- a/services/core/java/com/android/server/SystemServerInitThreadPool.java
+++ b/services/core/java/com/android/server/SystemServerInitThreadPool.java
@@ -44,7 +44,7 @@
 
     private static SystemServerInitThreadPool sInstance;
 
-    private ExecutorService mService = ConcurrentUtils.newFixedThreadPool(2,
+    private ExecutorService mService = ConcurrentUtils.newFixedThreadPool(4,
             "system-server-init-thread", Process.THREAD_PRIORITY_FOREGROUND);
 
     public static synchronized SystemServerInitThreadPool get() {