Don't touch system_ce until the first user unlock.

This CL does the following things:
1) Only start PersistQueue when the first user unlocked.
2) Only create recent task folder when we need to write the first file
to it.

Bug: 124697664
Test: Manual test -- checked recent_tasks, recent_images and
launch_params folders are still created correctly. No encryption policy
log seen.
Change-Id: I5b8bf712a3c45092b463622731d58f90d76fec58
diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index 75f299c..bda52b9 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -948,7 +948,7 @@
         @Override
         public void onUnlockUser(int userId) {
             synchronized (mService.getGlobalLock()) {
-                mService.mStackSupervisor.mLaunchParamsPersister.onUnlockUser(userId);
+                mService.mStackSupervisor.onUserUnlocked(userId);
             }
         }