core: change the signature of handleVdsMaintenanceTimeout

VdsEventListener#handleVdsMaintenanceTimeout can get just the ID
of the host and not the whole VDS object.

Change-Id: Iaa4a4815a1bf69ccae33bb37773a2a1a3b99a02e
Signed-off-by: Arik Hadas <ahadas@redhat.com>