Describe the bug
Stop does not report failures to stop an instance and exits with 0.

To Reproduce

1. multipass shell
2. inside the instance:
   1. sudo fsfreeze --freeze /
   2. sudo ip link set ens3 down
3. back outside, multipass stop
4. Observe the command exits with success and without reporting any error, even though the instance is still running.

Expected behavior
The stop command would report the failure to stop the instance and exit with an error code.

Additional info

• OS: Linux
• multipass version 1.12.0-dev.123+gdc4cbef6
• multipass get local.driver QEMU

Additional context
Related to #2906