MM-53107 Add setting to limit the max number of markdown nodes (#24414)

* MM-53107 Add setting to limit the max number of markdown nodes

* Add extra validation for a couple config fields

* Add new setting to telemetry

server/public/model/config.go

@@ -3149,7 +3149,8 @@ func (s *MessageExportSettings) SetDefaults() {
 }
 
 type DisplaySettings struct {
-	CustomURLSchemes     []string `access:"site_customization"`
+	CustomURLSchemes     []string `access:"site_posts"`
+	MaxMarkdownNodes     *int     `access:"site_posts"`
 	ExperimentalTimezone *bool    `access:"experimental_features"`
 }
 
@@ -3159,6 +3160,10 @@ func (s *DisplaySettings) SetDefaults() {
 		s.CustomURLSchemes = customURLSchemes
 	}
 
+	if s.MaxMarkdownNodes == nil {
+		s.MaxMarkdownNodes = NewInt(0)
+	}
+
 	if s.ExperimentalTimezone == nil {
 		s.ExperimentalTimezone = NewBool(true)
 	}
@@ -3502,6 +3507,10 @@ func (o *Config) IsValid() *AppError {
 		return appErr
 	}
 
+	if appErr := o.ExperimentalSettings.isValid(); appErr != nil {
+		return appErr
+	}
+
 	if appErr := o.SqlSettings.isValid(); appErr != nil {
 		return appErr
 	}
@@ -3577,6 +3586,10 @@ func (s *TeamSettings) isValid() *AppError {
 		return NewAppError("Config.IsValid", "model.config.is_valid.max_channels.app_error", nil, "", http.StatusBadRequest)
 	}
 
+	if *s.UserStatusAwayTimeout <= 0 {
+		return NewAppError("Config.IsValid", "model.config.is_valid.user_status_away_timeout.app_error", nil, "", http.StatusBadRequest)
+	}
+
 	if *s.MaxNotificationsPerChannel <= 0 {
 		return NewAppError("Config.IsValid", "model.config.is_valid.max_notify_per_channel.app_error", nil, "", http.StatusBadRequest)
 	}
@@ -3596,6 +3609,14 @@ func (s *TeamSettings) isValid() *AppError {
 	return nil
 }
 
+func (s *ExperimentalSettings) isValid() *AppError {
+	if *s.LinkMetadataTimeoutMilliseconds <= 0 {
+		return NewAppError("Config.IsValid", "model.config.is_valid.link_metadata_timeout.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}
+
 func (s *SqlSettings) isValid() *AppError {
 	if *s.AtRestEncryptKey != "" && len(*s.AtRestEncryptKey) < 32 {
 		return NewAppError("Config.IsValid", "model.config.is_valid.encrypt_sql.app_error", nil, "", http.StatusBadRequest)