CLOUDSTACK-5666 Cant remove a nic when a vm is in the Stopped state

When VM is not running, existing code is unable to retrieve associated cluster's Id. Now we will try to get this information using previous host where the VM was running.

Signed-off-by: Sateesh Chodapuneedi <sateesh@apache.org>
CLOUDSTACK-5662: XenServer can't discover iSCSI targets with different credentials