Ensure service unbind when receiving a null call screening service in onBind. am: 9b52d571e9 am: 1dbcbab4b3

Original change: https://googleplex-android-review.googlesource.com/c/platform/cts/+/21225922

Change-Id: Ifc27587d40b3269bedf331fd4dd0ca4c63ba907c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>