Do not allow home screen only wallpaper if current is the default am: 7742666ea7 am: cd23f3d5f0 am: d7b612fbb9 am: dffa981683

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/WallpaperPicker2/+/15567276

Change-Id: I635086361e61bbbda568c57b793ebe457c9ec5b7