Use STREAM_VOICE_CALL for ToneGenerator

Previously, we used STREAM_BLUETOOTH_SCO for ringback,
which is incorrect as ringback can not be heard when
using this stream type.

Flag: com.android.server.telecom.flags.use_stream_voice_call_tones
Bug: 363262590
Test: Manual SCO ringback tests, atest TelecomUnitTests
Change-Id: I564e5a0b9852e4570a650e53d869f40aa97d1c2f