Calling start() on a remote track multiple times creates multiple looping monitors

[wcarle]

When calling start() on RemoteTrack it calls this.monitorReceiver() which then calls itself with:

    setTimeout(() => {
      this.monitorReceiver();
    }, monitorFrequency);

This means that if you call start again on a remote track it will create a new setTimout loop. This can lead to a case where there are many redundant monitorReceiver calls on the same RemoteTrack if you call start on a track multiple times