Merge "Revert "Track last known RAT in voice call."" into tm-qpr-dev am: 4683069b am: b3d56073

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/opt/telephony/+/20171706



Change-Id: I02598939713f8de0d70b7285b402cc5662b613c3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>