Stop using hidden TelephonyProperties and PhoneConstants

Move the video-call related constants to TelecomManager since Telecom is
the only consumer. Also query from sysprop.TelephonyProperties instead
of the hidden one in telephony.

Bug: 147845600
Bug: 146834818
Test: manually make a video call and verify audio route
Change-Id: I2bdf19d14e9d9359b5dd0b09481f3397986d7f1c