Previously, we would set the state of the syncer after sending the msg,
which has the following flow,
1. In state `queryNewChannels`, we send the msg `QueryShortChanIDs`.
2. Once the msg is sent, we change to state `waitingQueryChanReply`.
But there's no guarantee the remote won't reply back inbetween the two
step. When that happens, our syncer would still be in state
`queryNewChannels`, causing the following error,
```
[ERR] DISC gossiper.go:873: Process query msg from peer [Alice] got unexpected msg *lnwire.ReplyShortChanIDsEnd received in state queryNewChannels
```
To fix it, we now make sure the state is updated before sending the msg.
yyforyongyu
37799b95b7