Fix full screen issue when switching between RTT and voice call.

Incall and answer screen is using transparent status and navigation bar, while RTT screen is using customized color. Switch between them require correct setting of system UI.

Bug: 67596257
Test: manually test to make RTT call and voice call, then switch between them.
PiperOrigin-RevId: 188956868
Change-Id: I3c17ff453be943f0b2ad28fe5cae434453fbe326
3 files changed