[SPARK-4802] [streaming] Remove receiverInfo once receiver is de-registered

  Once the streaming receiver is de-registered at executor, the `ReceiverTrackerActor` needs to
remove the corresponding reveiverInfo from the `receiverInfo` map at `ReceiverTracker`.
The only difference with the above approach is that, the receiverInfo (at the ReceiverTracker) is not up-to-date (if we remove this line) **at least** with what is being sent to the StreamingListenerBus. Does the below approach make sense?
```
receiverInfo -= streamId
listenerBus.post(StreamingListenerReceiverStopped(newReceiverInfo))
```