image-copy extension creates images without managed disks and bad snapshot uri

### Extension name (the extension in question)

image-copy extension

### Description of issue (in as much detail as possible)

It seems that an image created in the destination with `az image copy` does not have osDisk.managed disk but only its snapshot.
Now the snapshot does not seem to be usable for anything else other than launching VMs from this image, the snapshot uri (id) includes the `image-copy-rg` as it resource group, this group is deleted by the extension at the end of its run.
- How to I get the direct usable uri to that snapshot ?

I need it to create vhd blobs for deployent to the marketplace. Right now I am forced to create a vm from the image, immediately generalize it and shut down, create a snapshot of its osdisk and use that snapshot as the source to `az storage blob copy` to a storage account blob. It is a major pain, takes a long time and open to various failures.