CLOUDSTACK-4587. System VMs fail to start when the primary storage that has the System VMs is put into maintenance.
During VM start while configuring its disk devices, obtain the matching disk for a volume in storage
using both the volume's path and volume's datastore information.
CLOUDSTACK-7371. [VMware] Enabling primary storage maintenance fails when storages are across cluster.
1. While destroying a ROOT volume do the lookup of the associated VM under the DC and not just cluster.
2. In case of VMware, during VM start if a volume is being recreated no need to detach the old volume because
we now expunge it immediately and don't wait for the storage cleanup task to run.