itest: make small manual rfq edge case faster

We lower the amounts for the manual rfq quote and the corresponding
invoice in order to make the payment fail faster. Previously we'd get
many layers of sharding over the payment which would lead to a timeout,
so we'd wait for that. Now with the lower amounts we're hitting the min
shard amount faster, leading to a NoRoute failure.

Author: GeorgeTsagk

itest/litd_custom_channels_test.go

@@ -2676,8 +2676,8 @@ func testCustomChannelsLiquidityEdgeCasesCore(ctx context.Context,
 	logBalance(t.t, nodes, assetID, "after manual rfq hodl")
 
 	// Edge case: Charlie negotiates a quote with Dave which has a low max
-	// amount (~170k sats). Then Charlie creates an invoice with a total
-	// amount slightly larger than the max allowed in the quote (200k sats).
+	// amount (~17k sats). Then Charlie creates an invoice with a total
+	// amount slightly larger than the max allowed in the quote (30k sats).
 	// Erin will try to pay that invoice with sats, in shards of max size
 	// 80k sats. Dave will eventually stop forwarding HTLCs as the RFQ HTLC
 	// tracking mechanism should stop them from being forwarded, as they
@@ -2688,7 +2688,7 @@ func testCustomChannelsLiquidityEdgeCasesCore(ctx context.Context,
 	res, err := charlieTap.RfqClient.AddAssetBuyOrder(
 		ctx, &rfqrpc.AddAssetBuyOrderRequest{
 			AssetSpecifier: &assetSpecifier,
-			AssetMaxAmt:    10_000,
+			AssetMaxAmt:    1_000,
 			Expiry:         uint64(inOneHour.Unix()),
 			PeerPubKey:     dave.PubKey[:],
 			TimeoutSeconds: 10,
@@ -2704,7 +2704,7 @@ func testCustomChannelsLiquidityEdgeCasesCore(ctx context.Context,
 	// manually generated, quote.
 	iResp, err := charlie.AddInvoice(ctx, &lnrpc.Invoice{
 		Memo:       "",
-		Value:      200_000,
+		Value:      30_000,
 		RPreimage:  bytes.Repeat([]byte{11}, 32),
 		CltvExpiry: 60,
 		RouteHints: []*lnrpc.RouteHint{{
@@ -2719,11 +2719,22 @@ func testCustomChannelsLiquidityEdgeCasesCore(ctx context.Context,
 	// Now Erin tries to pay the invoice. Since rfq quote cannot satisfy the
 	// total amount of the invoice this payment will fail.
 	payInvoiceWithSatoshi(
-		t.t, erin, iResp, withPayErrSubStr("context deadline exceeded"),
-		withFailure(lnrpc.Payment_FAILED, failureNone),
-		withGroupKey(groupID),
+		t.t, erin, iResp,
+		withFailure(lnrpc.Payment_FAILED, failureNoRoute),
+		withGroupKey(groupID), withSmallShards(),
 	)
 
+	// Let's also cancel the invoice and assert that no HTLCs are still
+	// in-flight.
+	_, err = charlie.InvoicesClient.CancelInvoice(
+		ctx, &invoicesrpc.CancelInvoiceMsg{
+			PaymentHash: iResp.RHash,
+		},
+	)
+	require.NoError(t.t, err)
+
+	assertNumHtlcs(t.t, dave, 0)
+
 	logBalance(t.t, nodes, assetID, "after small manual rfq")
 
 	// Edge case: Fabia creates an invoice which Erin cannot satisfy with