multipass stop --force can not stop suspended vm if it does not have a suspend tag

[georgeliao]

Describe the bug
multipass stop --force can not stop suspended vm if it does not have a suspend tag

To Reproduce
How, and what happened?

1. multipass launch -n vm1
2. Manually delete the snapshot tag of the qemu image. qemu-img snapshot -d suspend <image_path_of_the_vm>
3. Run multipass stop vm1 --force or multipass delete vm1 --purge
   stop failed: Failed to delete suspend image: qemu-img failed (Process returned exit code: 1) with output:
   qemu-img: Could not delete snapshot 'suspend': snapshot not found

Expected behavior
What did you expect to happen?
Despite the faulty state (lacking a suspend tag but suspended) the VM is in, it should still delete or stop the VM forcefully.

Additional info

• OS: ubuntu 24.04
• multipass version: 1.14.0
• multipass get local.driver: qemu

Additional context
It is a very unusual state to get into, however, it did happen. Thus, to make the code more robust, it would be nice to handle the state gracefully.