PanelQueryState: restore comment

public/app/features/dashboard/state/PanelQueryState.ts

@@ -274,6 +274,8 @@ export class PanelQueryState {
 
     return {
       state: done ? LoadingState.Done : LoadingState.Streaming,
+      // This should not be needed but unfortunately Prometheus datasource sends non DataFrame here bypassing the
+      // typings
       series: this.sendFrames ? getProcessedDataFrames(series) : [],
       legacy: this.sendLegacy ? translateToLegacyData(series) : undefined,
       request: {