datasources: query-service url fix (#105178)

packages/grafana-runtime/src/utils/DataSourceWithBackend.ts

@@ -226,7 +226,7 @@ class DataSourceWithBackend<
         if (!hasExpr && dsUIDs.size === 1) {
           // TODO? can we talk directly to the apiserver?
         }
-        url = `/apis/query.grafana.app/v0alpha1/namespaces/${config.namespace}/query?ds_type=' + this.type`;
+        url = `/apis/query.grafana.app/v0alpha1/namespaces/${config.namespace}/query?ds_type=${this.type}`;
       }
     }