fix cloning/restoring of cloudinit disks in raw format

fix cloning/restoring of cloudinit disks in raw format

We only added the format extension when it was not 'raw'. But on file level
storages we always require it. To fix this, always add the format
extension if the storage provides the 'path' property.
This is the same logic we use in create_disks for cloudinit disks.

Signed-off-by: Mira Limbeck <m.limbeck@proxmox.com>