Describe the bug
If multipass can't stop an instance normally, it will keep running even after deleted.

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 instance still running after the command exits (which, by the way...)
5. multipass delete primary
6. pgrep -fa qemu and observe the process still running
7. multipass recover primary
8. multipass list observe primary still running

Expected behavior
Delete would kill the instance if regular stopping did not work.

Additional info

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

Additional context
This should be fixable by force-stopping after #1909 is in.