DO NOT MERGE DSDA: Set call EXTRA if either sub doesn't allow hold

- When either the existing call or the incoming call is on a
  non-hold-supported carrier, answering the incoming call should
  disconnect the existing call.
- TelephonyConnectionService takes care of both setting the call extra
  on receiving an incoming call, and terminating the existing call when
  the incoming call is answered.
- Dialer UX presentation and behavior remains unchanged.

Bug: 307541196
Bug: 315993953
Test: Live test with VZW + TMO DSDA, updated TelephonyConnectionServiceTest.
Change-Id: I72cef9d6c8f9932d3b3d3974029e27b6788f9713
3 files changed