[automerger skipped] Configure existing ThemePicker Robolectric tests to run with atest. am: a2724423d5 -s ours

am skip reason: Merged-In I25c4efdb73dc5eb88611efac669de13fa2be0c3d with SHA-1 9a9c7c1809 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/20639269

Change-Id: I9582be11244c1a5129799ae9903e4aee343bd382
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>