Pyroscope: Fix wrong defaults when importing query from different datasource (#69307)

public/app/plugins/datasource/phlare/datasource.ts

@@ -82,8 +82,7 @@ export class PhlareDataSource extends DataSourceWithBackend<Query, PhlareDataSou
       labelSelector: toPromLikeExpr(labelBasedQuery),
       queryType: 'both',
       profileTypeId: '',
-      maxNodes: 16,
-      groupBy: [''],
+      groupBy: [],
     };
   }