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

@@ -3068,7 +3068,7 @@ 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,
@@ -3084,7 +3084,7 @@ 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{{
@@ -3099,11 +3099,22 @@ 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