Retain allowBackup annotation when system+lock wallpaper becomes lock only

Bug 32069467

Change-Id: I5d0b91c40e1a2896f2b11efeef7bff84503cf2c0
diff --git a/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java b/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java
index 760e298..3720940 100644
--- a/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java
+++ b/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java
@@ -1487,7 +1487,7 @@
         lockWP.cropHint.set(sysWP.cropHint);
         lockWP.width = sysWP.width;
         lockWP.height = sysWP.height;
-        lockWP.allowBackup = false;
+        lockWP.allowBackup = sysWP.allowBackup;
 
         // Migrate the bitmap files outright; no need to copy
         try {