Use framework-tethering-stub instead of framework-tethering

The non-updatable part of the platform now is built with
framework-tethering-stub, which is a stub library of
framework-tethering.

Bug: 147200698
Test: m
Change-Id: I97ef83f7f9b4c1376f373713036f5256318f1050
Merged-In: I97ef83f7f9b4c1376f373713036f5256318f1050