update vm terminate logic and remove old database connection code
update vm terminate logic and remove old database connection code

After successfully terminating a vm the poller now updates the vm database row to
terminate=2 so it doesn't attempt to terminate again if another command cycle
runs before the vm poller removes the terminated vm from the database.

hep-gc/cloudscheduler,hep-gc/cloudscheduler,hep-gc/cloudscheduler,hep-gc/cloudscheduler