CLOUDSTACK-4123: 3.0.6 to ASF 4.2 Upgrade: On Adding VMWare Cluster to the Setup, 3.0.6 System VM Template for VMWare is downloaded instead of 4.2

Updating the new system template URLs for the existing templates during upgrade to 4.2.
If new 4.2 system template is registered before upgrade then marking the old templates as removed during upgrade.