CLOUDSTACK-8126. Cold Migration of VM is not working as expected. In case a VM is cold migrated across clusters then VM fails to start.
1. If a VM by the same name exists on a different cluster in the VMware DC, unregister the existing VM and continue with the VM start.
2. If VM start succeeds, delete VM files associated with the unregistered VM.
3. If VM start fails, re-register the unregistered VM.