multi: introduce config-level DustThreshold for defining threshold

lntest/itest/lnd_test.go

@@ -203,6 +203,7 @@ func TestLightningNetworkDaemon(t *testing.T) {
 	// TODO(roasbeef): create master balanced channel with all the monies?
 	aliceBobArgs := []string{
 		"--default-remote-max-htlcs=483",
+		"--dust-threshold=5000000",
 	}
 
 	// Run the subset of the test cases selected in this tranche.