MEDIUM: backend: Rely on addresses at stream level to init server connection

MEDIUM: backend: Rely on addresses at stream level to init server connection

Client source and destination addresses at stream level are used to initiate
the connections to a server. For now, stream-interface addresses are never
set. So, thanks to the fallback mechanism, no changes are expected with this
patch. But its purpose is to rely on addresses at the appropriate level when
set instead of those at the connection level.