Surface inventory errors so as to not generate bad successful builds
Several builds of the same pipeline were green but didn't generate a valid VM image:
- https://gitlab.com/gitlab-org/ci-cd/shared-runners/images/macstadium/orka/-/jobs/751232182#L86
- https://gitlab.com/gitlab-org/ci-cd/shared-runners/images/macstadium/orka/-/jobs/751232178#L86
- https://gitlab.com/gitlab-org/ci-cd/shared-runners/images/macstadium/orka/-/jobs/751232179#L785 (failed to connect to VM for reboot)
Since by design Ansible doesn't return an error code if no hosts are matched, we should at least fail the build if the inventory doesn't return the expected VM.