MM-43077 Allow inline JSON in config.json for advanced logging config (#23324)

* add AdvancedLoggingJSON to LogSettings and deprecate AdvancedLoggingConfig
* allow embedded JSON in config for advanced logging.

server/channels/app/audit.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/mattermost/mattermost-server/server/public/model"
 	"github.com/mattermost/mattermost-server/server/public/shared/mlog"
+	"github.com/mattermost/mattermost-server/server/public/utils"
 	"github.com/mattermost/mattermost-server/server/v8/channels/audit"
 	"github.com/mattermost/mattermost-server/server/v8/channels/store"
 	"github.com/mattermost/mattermost-server/server/v8/config"
@@ -109,14 +110,14 @@ func (s *Server) configureAudit(adt *audit.Audit, bAllowAdvancedLogging bool) er
 	adt.OnError = s.onAuditError
 
 	var logConfigSrc config.LogConfigSrc
-	dsn := *s.platform.Config().ExperimentalAuditSettings.AdvancedLoggingConfig
-	if bAllowAdvancedLogging && dsn != "" {
+	dsn := s.platform.Config().ExperimentalAuditSettings.GetAdvancedLoggingConfig()
+	if bAllowAdvancedLogging && !utils.IsEmptyJSON(dsn) {
 		var err error
 		logConfigSrc, err = config.NewLogConfigSrc(dsn, s.platform.GetConfigStore())
 		if err != nil {
 			return fmt.Errorf("invalid config source for audit, %w", err)
 		}
-		mlog.Debug("Loaded audit configuration", mlog.String("source", dsn))
+		mlog.Debug("Loaded audit configuration", mlog.String("source", string(dsn)))
 	}
 
 	// ExperimentalAuditSettings provides basic file audit (E0, E10); logConfigSrc provides advanced config (E20).