Bug: When custom image is imported on a cloud platform, we fail to detect the cloud it is running on

[lucasmoura]

Description of the bug

When users import an image into a cloud platform and try to in-place upgrade it to a Pro image, the auto-attach operation fails, as we cannot detect which the cloud through cloud-id. That is because the cloud-init operation has already been applied on the original machine and we don't reprocess when launching the same image on the cloud.

Expected behavior

Even if cannot properly fix this issue, we should at least provide a better error message to our users

Current behavior

Right now, when that happens, users will see the following error message:

Auto-attach image support is not available on none
See: https://canonical-ubuntu-pro-client.readthedocs-hosted.com/en/latest/explanations/what_are_ubuntu_pro_cloud_instances.html

To Reproduce

1. Create a ubuntu server VM
2. Export the image (i.e. in the OVM format)
3. Import the image into AWS platform
4. Upgrade to Pro using AWS License manager
5. Verify that pro auto-attach fails