Ensure service unbind when receiving a null call screening service in onBind. am: 14927c6f0b am: a005a8529a am: 3d3098da90

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/services/Telecomm/+/21224930

Change-Id: I7f6f468a57ad27fff8991cd97a67811ca42f08a1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>