audio: Fix BT AIDL HAL module implementation

In order to align with legacy behavior, when opening a stream,
the module must suggest the current configuration of the BT session.
For that to work, the BT device proxy must be opened prior
to creating a stream, code moved to ModuleBluetooth.

Fix minor inconsistencies and bugs found during testing.

Bug: 301213930
Bug: 316027906
Test: atest pts-bot
Change-Id: I04ddaf73be82f872a3f32a789563c3cbd648eb61
diff --git a/bluetooth/audio/utils/aidl_session/BluetoothAudioSession.cpp b/bluetooth/audio/utils/aidl_session/BluetoothAudioSession.cpp
index c057505..67ba93c 100644
--- a/bluetooth/audio/utils/aidl_session/BluetoothAudioSession.cpp
+++ b/bluetooth/audio/utils/aidl_session/BluetoothAudioSession.cpp
@@ -500,14 +500,12 @@
                << " has NO session";
     return false;
   }
-  bool retval = false;
-
   if (!stack_iface_->getPresentationPosition(&presentation_position).isOk()) {
     LOG(WARNING) << __func__ << " - IBluetoothAudioPort SessionType="
                  << toString(session_type_) << " failed";
     return false;
   }
-  return retval;
+  return true;
 }
 
 void BluetoothAudioSession::UpdateSourceMetadata(