tmf-remote: use dispose instead of disconnect for a fetch connection

tmf-remote: use dispose instead of disconnect for a fetch connection

This ensures that the connection stays up if it connection had
been establieshed before the fetching of log procedure.

Change-Id: I056a6c2632a2b9dc33fbe7504c48889e98567dc3
Signed-off-by: Bernd Hufmann <Bernd.Hufmann@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/44869
Reviewed-by: Hudson CI
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
Tested-by: Patrick Tasse <patrick.tasse@gmail.com>