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/channels/app/platform/helper_test.go

@@ -143,8 +143,8 @@ func setupTestHelper(dbStore store.Store, enterprise bool, includeCacheLayer boo
 	*memoryConfig.AnnouncementSettings.AdminNoticesEnabled = false
 	*memoryConfig.AnnouncementSettings.UserNoticesEnabled = false
 	*memoryConfig.MetricsSettings.Enable = true
-	*memoryConfig.ServiceSettings.ListenAddress = ":0"
-	*memoryConfig.MetricsSettings.ListenAddress = ":0"
+	*memoryConfig.ServiceSettings.ListenAddress = "localhost:0"
+	*memoryConfig.MetricsSettings.ListenAddress = "localhost:0"
 	configStore.Set(memoryConfig)
 
 	ps, err := New(ServiceConfig{