fix the lsps2 cltv delta check

It was wrongly assumed that the lsp had to enforce a cltv delta +2. It is
actually the recipient creating invoices with a cltv delta +2, but the LSP does
not have anything to do with that.

itest/lspd_test.go

@@ -210,11 +210,6 @@ var allTestCases = []*testCase{
 		test:    testLsps2HappyFlow,
 		isLsps2: true,
 	},
-	{
-		name:    "testLsps2Cltv",
-		test:    testLsps2Cltv,
-		isLsps2: true,
-	},
 	{
 		name:    "testLsps2NoBalance",
 		test:    testLsps2NoBalance,