[Discovery] Handle ConnectionTransportException during a Master/Node fault detection ping

Both the Master and Node fault detection register themselves to be notified when a node disconnects to be able to respond to it accordingly. As such, when a ConnectionTransportException was raised on a ping request, it was not handled as it is already handled somewhere else. However, this does introduce a racing condition, if the disconnect  happen during a period where there is no current master (minimum_master_node breach) at which time the fault detection is not active. In this case, we will only discover the disconnect error during the ping request, so we have to respond accordingly.

Closes #6686