itest: end to end route blinding invoices test

Update one of the route blinding itests to do a full end-to-end test
where the recipient generates and invoice with a blinded path and the
sender just provides that invoice to SendPayment.

The tests also covers the edge case where the recipient is the
introduction node.

itest/list_on_test.go

@@ -563,8 +563,8 @@ var allTestCases = []*lntest.TestCase{
 		TestFunc: testQueryBlindedRoutes,
 	},
 	{
-		Name:     "forward and receive blinded",
-		TestFunc: testForwardAndReceiveBlindedRoute,
+		Name:     "route blinding invoices",
+		TestFunc: testBlindedRouteInvoices,
 	},
 	{
 		Name:     "receiver blinded error",