Bluetooth in band ring

Prevent the telecom service from generating a ringer if there is already
a ringer generated by a phone connected over bluetooth headset client
service.

Bug: 65673832
Test: runtest telecom-unit -c
com.android.server.telecom.tests.RingerTest
Change-Id: If232fc3c6d75bd24557162682e9cd4a900afcee4