multi: use separate cltv expiry field from invoice

Now that the Invoice struct contains the decoded final cltv delta value,
the decoding of payment requests can be removed from the invoice
registry.

htlcswitch/mock.go

@@ -768,13 +768,9 @@ func newMockRegistry(minDelta uint32) *mockInvoiceRegistry {
 		panic(err)
 	}
 
-	decodeExpiry := func(invoice string) (uint32, error) {
-		return testInvoiceCltvExpiry, nil
-	}
-
 	finalCltvRejectDelta := int32(5)
 
-	registry := invoices.NewRegistry(cdb, decodeExpiry, finalCltvRejectDelta)
+	registry := invoices.NewRegistry(cdb, finalCltvRejectDelta)
 	registry.Start()
 
 	return &mockInvoiceRegistry{
@@ -783,7 +779,9 @@ func newMockRegistry(minDelta uint32) *mockInvoiceRegistry {
 	}
 }
 
-func (i *mockInvoiceRegistry) LookupInvoice(rHash lntypes.Hash) (channeldb.Invoice, uint32, error) {
+func (i *mockInvoiceRegistry) LookupInvoice(rHash lntypes.Hash) (
+	channeldb.Invoice, error) {
+
 	return i.registry.LookupInvoice(rHash)
 }