Do not purge process groups on system_server startup

Removing all process groups during system_server startup can race with
process group creation from init which results in occasional failure to
create a process group and failure to boot the device.
Move process group purging into init to prevent such a race.

Bug: 228160715
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I2e50f53c9692424c994c0b4ee6f1e2762632c3bc

services/core/java/com/android/server/am/ActivityManagerService.java

@@ -91,7 +91,6 @@ import static android.os.Process.killProcessQuiet;
 import static android.os.Process.myPid;
 import static android.os.Process.myUid;
 import static android.os.Process.readProcFile;
-import static android.os.Process.removeAllProcessGroups;
 import static android.os.Process.sendSignal;
 import static android.os.Process.setThreadPriority;
 import static android.os.Process.setThreadScheduler;
@@ -2388,8 +2387,6 @@ public class ActivityManagerService extends IActivityManager.Stub
     }
 
     private void start() {
-        removeAllProcessGroups();
-
         mBatteryStatsService.publish();
         mAppOpsService.publish();
         Slog.d("AppOps", "AppOpsService published");