Do not check for xscontainer on XCP-ng

[borzel]

https://xcp-ng.org/forum/topic/82/xcp-ng-center-no-cloud-init-cloud-config-options-in-vm-properties-in/22

Extend this function, so that on XCP-ng hosts it always return true.

public static bool ContainerCapability(IXenConnection connection)
       {
           var master = GetMaster(connection);
           if (master == null)
               return false;
           if (ElyOrGreater(connection))
               return master.AppliedUpdates().Any(update => update.Name().ToLower().StartsWith("xscontainer")); 
           return CreamOrGreater(connection) && master.SuppPacks().Any(suppPack => suppPack.Name.ToLower().StartsWith("xscontainer")); 
       }

[borzel]

Should now work with XCP-ng Center 7.4.2-RC2:
https://github.com/xcp-ng/xenadmin/releases/tag/v7.4.2-RC2