during shutdown there is a window after we have stopped TCP and disconnected from...

during shutdown there is a window after we have stopped TCP and disconnected from all other nodes but before we have stopped all processing.

During this window we may still hit asynchronous events that will fail because we can not send/receive packets from other nodes.

These messages are logged as ... Transport is DOWN. To help indicate that they are benign messages related to the process of shutting down.

These messages spam the syslog during normal shutdown, so this patch will drop the loglevel of these messages to DEBUG, so that they will not appear in or spam the syslog.