AudioService: fix uid check in setBluetoothScoOn

Calling UID is now checked in setBluetoothScoOn and only allow
route to change if request comes from a system component.

The check was not taking into account secondary users, hence
causing failure to route audio to SCO when secondary users
were active.

This change makes sure we are checking the correct app id,
without taking into account the user id.

Bug: 74057977
Test: SCO call using Guest User

Change-Id: I3e26dedb6333a85b315073fe4830c4d1b8070742