Fix AdvancedLoggingConfig validation (#25304)

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/config.go

@@ -1292,7 +1292,7 @@ func NewLogSettings() *LogSettings {
 
 func (s *LogSettings) isValid() *AppError {
 	cfg := make(mlog.LoggerConfiguration)
-	err := json.Unmarshal(s.GetAdvancedLoggingConfig(), &cfg)
+	err := json.Unmarshal(s.AdvancedLoggingJSON, &cfg)
 	if err != nil {
 		return NewAppError("LogSettings.isValid", "model.config.is_valid.log.advanced_logging.json", map[string]any{"Error": err}, "", http.StatusBadRequest).Wrap(err)
 	}

server/public/model/config_test.go

@@ -1297,6 +1297,12 @@ func TestLogSettingsIsValid(t *testing.T) {
 			},
 			ExpectError: false,
 		},
+		"AdvancedLoggingConfig contains filepath": {
+			LogSettings: LogSettings{
+				AdvancedLoggingConfig: sToP("/some/Path"),
+			},
+			ExpectError: false,
+		},
 	} {
 		t.Run(name, func(t *testing.T) {
 			test.LogSettings.SetDefaults()