Don't show the border for the unselected wallpapers. am: 4cd5690762 am: 61413eb240

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/WallpaperPicker2/+/11597921

Change-Id: I0dac6bf3c99f151d6ec92af462208b19f34e547b