Force jenkins win slave to disconnect and reboot when slave exits

To fix issues where jenkins win slave gives an exception right
after starting a job. The problem seems to be unreliable
network connection, where master never gets the information
that the node went down. With this fix we send the disconnect
again and let the node register itself again normally after
re-boot.

Task-number: QTQAINFRA-846
Change-Id: I6e71fc49e6a881b5703bc7619a53c9a7e58a36a3
Reviewed-by: Sergio Ahumada <sahumada@blackberry.com>