MM-58092 Add feature flag and setting for client performance metrics (#26942)

* MM-58092 Add feature flag and setting for client performance metrics

* Fix incorrect field name

server/public/model/config.go

@@ -980,9 +980,10 @@ func (s *ClusterSettings) SetDefaults() {
 }
 
 type MetricsSettings struct {
-	Enable           *bool   `access:"environment_performance_monitoring,write_restrictable,cloud_restrictable"`
-	BlockProfileRate *int    `access:"environment_performance_monitoring,write_restrictable,cloud_restrictable"`
-	ListenAddress    *string `access:"environment_performance_monitoring,write_restrictable,cloud_restrictable"` // telemetry: none
+	Enable              *bool   `access:"environment_performance_monitoring,write_restrictable,cloud_restrictable"`
+	BlockProfileRate    *int    `access:"environment_performance_monitoring,write_restrictable,cloud_restrictable"`
+	ListenAddress       *string `access:"environment_performance_monitoring,write_restrictable,cloud_restrictable"` // telemetry: none
+	EnableClientMetrics *bool   `access:"environment_performance_monitoring,write_restrictable,cloud_restrictable"`
 }
 
 func (s *MetricsSettings) SetDefaults() {
@@ -997,6 +998,10 @@ func (s *MetricsSettings) SetDefaults() {
 	if s.BlockProfileRate == nil {
 		s.BlockProfileRate = NewInt(0)
 	}
+
+	if s.EnableClientMetrics == nil {
+		s.EnableClientMetrics = NewBool(true)
+	}
 }
 
 type ExperimentalSettings struct {

server/public/model/feature_flags.go

@@ -55,6 +55,8 @@ type FeatureFlags struct {
 	WebSocketEventScope bool
 
 	NotificationMonitoring bool
+
+	ClientMetrics bool
 }
 
 func (f *FeatureFlags) SetDefaults() {
@@ -78,6 +80,7 @@ func (f *FeatureFlags) SetDefaults() {
 	f.ChannelBookmarks = false
 	f.WebSocketEventScope = false
 	f.NotificationMonitoring = true
+	f.ClientMetrics = false
 }
 
 // ToMap returns the feature flags as a map[string]string