Only move VMs to poweroff when monitor is 3*monitor_interaval from RUNNING start time

(cherry picked from commit 4236b0f2288b4eafc50e8315f4640a70a984f96f)
Reduce power-off threshold to 2*monitor-period

(cherry picked from commit f902ac76e872648475aacca1d10c8d5781399dbb)