bind to localhost:0 for tests (#22839)

* bind to localhost:0 for tests

Explicitly bind to `localhost:0` instead of just `:0` to avoid binding to all available interfaces and in turn avoid triggering firewall warnings on MacOS.

* fix Playbooks to use dynamic port

* TestMetrics: handle ipv4 localhost too

* TestMetrics: linting

server/playbooks/server/main_test.go

@@ -6,6 +6,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -117,7 +118,7 @@ func Setup(t *testing.T) *TestEnvironment {
 	config := configStore.Get()
 	// Force plugins to be disabled since we are in product mode
 	config.PluginSettings.Enable = model.NewBool(false)
-	config.ServiceSettings.ListenAddress = model.NewString("localhost:9056")
+	config.ServiceSettings.ListenAddress = model.NewString("localhost:0")
 	config.TeamSettings.MaxUsersPerTeam = model.NewInt(10000)
 	config.LocalizationSettings.SetDefaults()
 	config.SqlSettings = *sqlSettings
@@ -218,7 +219,7 @@ func (e *TestEnvironment) CreateClients() {
 	require.Nil(e.T, appErr)
 	e.RegularUserNotInTeam = notInTeam
 
-	siteURL := "http://localhost:9056"
+	siteURL := fmt.Sprintf("http://localhost:%v", e.A.Srv().ListenAddr.Port)
 
 	serverAdminClient := model.NewAPIv4Client(siteURL)
 	_, _, err := serverAdminClient.Login(admin.Email, userPassword)