Customize the service class for Call barring

Add a new carrier config that changes the service class is used for Call
barring settings.

CP from aosp/1404668

Test: manual
Bug: 161772958

Merged-In: Ibce22d0d340ce648c0b6df411266d1c4fe537013
Change-Id: Ibce22d0d340ce648c0b6df411266d1c4fe537013