Merge " Improve AllowedNetworkTypesReason and refactor PreferredNetworkType" am: 8c26f14514 am: ab7c79e3db

Original change: https://android-review.googlesource.com/c/platform/packages/services/Telephony/+/1615179

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ibb5ebed3656dfec02381de9e274065c61171cae1