lnd+rpcserver: use same serverOpts for custom listeners

Earlier we used emtpy grpc server options if custom listeners were set.
This was done to disable TLS. Now, we reuse the same server options as
for the regular listeners, in a move towards enabling TLS also here.

rpcserver.go

@@ -508,10 +508,11 @@ var _ lnrpc.LightningServer = (*rpcServer)(nil)
 // base level options passed to the grPC server. This typically includes things
 // like requiring TLS, etc.
 func newRPCServer(s *server, macService *macaroons.Service,
-	subServerCgs *subRPCServerConfigs, restDialOpts []grpc.DialOption,
-	restProxyDest string, atpl *autopilot.Manager,
-	invoiceRegistry *invoices.InvoiceRegistry, tower *watchtower.Standalone,
-	tlsCfg *tls.Config, getListeners rpcListeners,
+	subServerCgs *subRPCServerConfigs, serverOpts []grpc.ServerOption,
+	restDialOpts []grpc.DialOption, restProxyDest string,
+	atpl *autopilot.Manager, invoiceRegistry *invoices.InvoiceRegistry,
+	tower *watchtower.Standalone, tlsCfg *tls.Config,
+	getListeners rpcListeners,
 	chanPredicate *chanacceptor.ChainedAcceptor) (*rpcServer, error) {
 
 	// Set up router rpc backend.
@@ -643,7 +644,7 @@ func newRPCServer(s *server, macService *macaroons.Service,
 	)
 
 	// Get the listeners and server options to use for this rpc server.
-	listeners, cleanup, serverOpts, err := getListeners()
+	listeners, cleanup, err := getListeners()
 	if err != nil {
 		return nil, err
 	}