Fix configz test failures (#13478)

* Fix configz test failures

* Dynamically assign port

pkg/ctrlz/ctrlz.go

@@ -195,7 +195,8 @@ func (s *Server) listen() {
 // Close is not normally used by programs that expose ControlZ, it is primarily intended to be
 // used by tests.
 func (s *Server) Close() {
-	log.Info("Closing closing ControlZ")
+	log.Info("Closing ControlZ")
+
 	if s.listener != nil {
 		if err := s.listener.Close(); err != nil {
 			log.Warnf("Error closing ControlZ: %v", err)

pkg/mcp/configz/client/configz_test.go

@@ -77,10 +77,14 @@ func TestConfigZ(t *testing.T) {
 	defer cancel()
 
 	o := ctrlz.DefaultOptions()
-	cz, _ := ctrlz.Run(o, []fw.Topic{CreateTopic(cl)})
+	o.Port = 0
+	cz, err := ctrlz.Run(o, []fw.Topic{CreateTopic(cl)})
+	if err != nil {
+		t.Fatal(err)
+	}
 	defer cz.Close()
 
-	baseURL := fmt.Sprintf("http://%s:%d", o.Address, o.Port)
+	baseURL := fmt.Sprintf("http://%v", cz.Address())
 
 	// wait for client to make first watch request
 	for {

pkg/mcp/configz/server/configz_test.go

@@ -22,11 +22,11 @@ import (
 	"testing"
 	"time"
 
+	"github.com/gogo/protobuf/types"
+
 	"istio.io/istio/pkg/mcp/source"
 	"istio.io/istio/pkg/mcp/testing/groups"
 
-	"github.com/gogo/protobuf/types"
-
 	"istio.io/istio/pkg/ctrlz"
 	"istio.io/istio/pkg/ctrlz/fw"
 	"istio.io/istio/pkg/mcp/snapshot"
@@ -52,10 +52,14 @@ func TestConfigZ(t *testing.T) {
 	s.Cache.SetSnapshot(groups.Default, b.Build())
 
 	o := ctrlz.DefaultOptions()
-	cz, _ := ctrlz.Run(o, []fw.Topic{CreateTopic(s.Cache)})
+	o.Port = 0
+	cz, err := ctrlz.Run(o, []fw.Topic{CreateTopic(s.Cache)})
+	if err != nil {
+		t.Fatal(err)
+	}
 	defer cz.Close()
 
-	baseURL := fmt.Sprintf("http://%s:%d", o.Address, o.Port)
+	baseURL := fmt.Sprintf("http://%v", cz.Address())
 
 	t.Run("configj with 1 request", func(tt *testing.T) { testConfigJWithOneRequest(tt, baseURL) })
 }