AudioDeviceBroker: fix communication route for idle apps

AudioDeviceBroker.onUpdateCommunicationRouteClient() was just evaluating
if SCO audio should be used by the audio policy for calls (which includes when SCO audio
is already active from an external  request - e.g. by Telecom) but not if no more active
request to use SCO exists. Thus it was failing to stop internal SCO audio requests when
no more communication route client was active.

Also fix a spurious CONNECTING intent broadcast in
BtHelper.requestScoState()

Bug: 294167472
Test: repro steps in bug
Change-Id: Ib94dc3aa8cfe7120a87661b6403ee4060a295f8c