XML config properly initialize WS message broker stats

Issue: SPR-14190

Author: rstoyanchev

spring-websocket/src/main/java/org/springframework/web/socket/config/MessageBrokerBeanDefinitionParser.java

@@ -620,10 +620,9 @@ private void registerWebSocketMessageBrokerStats(RootBeanDefinition broker, Runt
 		if (context.getRegistry().containsBeanDefinition(name)) {
 			beanDef.getPropertyValues().add("outboundChannelExecutor", context.getRegistry().getBeanDefinition(name));
 		}
-		name = SCHEDULER_BEAN_NAME;
-		if (context.getRegistry().containsBeanDefinition(name)) {
-			beanDef.getPropertyValues().add("sockJsTaskScheduler", context.getRegistry().getBeanDefinition(name));
-		}
+		Object scheduler = WebSocketNamespaceUtils.registerScheduler(SCHEDULER_BEAN_NAME, context, source);
+		beanDef.getPropertyValues().add("sockJsTaskScheduler", scheduler);
+
 		registerBeanDefByName("webSocketMessageBrokerStats", beanDef, context, source);
 	}