MINOR: frontend: Rely on client src and dst addresses at stream level

MINOR: frontend: Rely on client src and dst addresses at stream level

For now, stream-interface or session addresses are never set. So, thanks to
the fallback mechanism, no changes are expected with this patch. But its
purpose is to rely on the client addresses at the stream level, when set,
instead of those at the connection level. The addresses are retrieved from
the frontend stream-interface.