mod+lntest: disable stall handler in btcd mining node

The latest version of btcd allows its stall handler to be disabled. We
use that new config option to make sure the mining btcd node and the lnd
chain backend btcd node aren't disconnected if some test takes too long
and no new p2p messages are exchanged.

lntest/btcd.go

@@ -90,6 +90,8 @@ func NewBackend(miner string, netParams *chaincfg.Params) (
 		// its requested data are not found. We add a nobanning flag to
 		// make sure they stay connected if it happens.
 		"--nobanning",
+		// Don't disconnect if a reply takes too long.
+		"--nostalldetect",
 	}
 	chainBackend, err := rpctest.New(netParams, nil, args, GetBtcdBinary())
 	if err != nil {

lntest/node.go

@@ -554,6 +554,8 @@ func NewMiner(baseLogDir, logFilename string, netParams *chaincfg.Params,
 		"--debuglevel=debug",
 		"--logdir=" + baseLogDir,
 		"--trickleinterval=100ms",
+		// Don't disconnect if a reply takes too long.
+		"--nostalldetect",
 	}
 
 	miner, err := rpctest.New(netParams, handler, args, btcdBinary)