fix plasmavmc kvm smoke shutdown test

plasmavmc/crates/plasmavmc-kvm/src/lib.rs

@@ -1416,9 +1416,9 @@ mod tests {
             "unexpected state: {:?}",
             status.actual_state
         );
-        backend
+        // The smoke path may use an empty qcow2, so there is no guest userspace to
-            .stop(&handle, Duration::from_secs(2))
+        // honor ACPI powerdown. Use force-kill here to validate QEMU launch
-            .await
+        // without depending on guest shutdown behavior.
-            .expect("stop vm");
+        backend.kill(&handle).await.expect("kill vm");
     }
 }