Move robolectric tests from 3.6.2 to 4.8.2 am: bc4cc094c7 am: 076c3c4581 am: d74eb9707a

Original change: https://android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/2292054

Change-Id: Ide0009fd1b88c7fb3a6fed6aaa5055901c67533e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>