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

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



Change-Id: I422a2c4c6a739145abfa08e2b5a54e00a040b614
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>