chainregistry: set minimum relay fee for static fee estimators

This is needed since the sweeper now relies on this being a being non-zero
value.

chainregistry.go

@@ -154,7 +154,7 @@ func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
 			TimeLockDelta: cfg.Bitcoin.TimeLockDelta,
 		}
 		cc.feeEstimator = lnwallet.NewStaticFeeEstimator(
-			defaultBitcoinStaticFeePerKW, 0,
+			defaultBitcoinStaticFeePerKW, lnwallet.FeePerKwFloor,
 		)
 	case litecoinChain:
 		cc.routingPolicy = htlcswitch.ForwardingPolicy{
@@ -164,7 +164,7 @@ func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
 			TimeLockDelta: cfg.Litecoin.TimeLockDelta,
 		}
 		cc.feeEstimator = lnwallet.NewStaticFeeEstimator(
-			defaultLitecoinStaticFeePerKW, 0,
+			defaultLitecoinStaticFeePerKW, lnwallet.FeePerKwFloor,
 		)
 	default:
 		return nil, fmt.Errorf("Default routing policy for chain %v is "+