Add TEST_MAPPING for DownloadProvider. am: 067c09636f am: a8486a85c8 am: d79fa86728

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/providers/DownloadProvider/+/11839720

Change-Id: I770831b501e2bbad6544571ee4d6f3a888c689a9