Dashboards: Make conversion data optional (#109965)

apps/dashboard/pkg/migration/conversion/testdata/output/v2alpha1.ds-data-query.v1beta1.json

@@ -1,4 +1,6 @@
 {
+  "kind": "Dashboard",
+  "apiVersion": "dashboard.grafana.app/v1beta1",
   "metadata": {
     "name": "test-v2alpha1-annotations",
     "creationTimestamp": null
@@ -7,8 +9,8 @@
   "status": {
     "conversion": {
       "failed": true,
-      "storedVersion": "v2alpha1",
-      "error": "backend conversion not yet implemented"
+      "error": "backend conversion not yet implemented",
+      "storedVersion": "v2alpha1"
     }
   }
 }