Fix AbstractMessageListenerContainer Javadoc regarding error log level

This commit updates AbstractMessageListenerContainer's Javadoc
regarding the log level used in invokeErrorHandler() so that the
documentation aligns with the implementation, namely that errors will
logged at WARN level if no ErrorHandler has been registered.

Closes gh-30730

spring-jms/src/main/java/org/springframework/jms/listener/AbstractMessageListenerContainer.java

@@ -46,7 +46,7 @@
  *
  * <p><b>NOTE:</b> The default behavior of this message listener container is to
  * <b>never</b> propagate an exception thrown by a message listener up to the JMS
- * provider. Instead, it will log any such exception at the error level.
+ * provider. Instead, it will log any such exception at {@code WARN} level.
  * This means that from the perspective of the attendant JMS provider no such
  * listener will ever fail. However, if error handling is necessary, then
  * an implementation of the {@link ErrorHandler} strategy may be provided to
@@ -877,7 +877,7 @@ else if (isSubscriptionDurable()) {
 
 	/**
 	 * Handle the given exception that arose during listener execution.
-	 * <p>The default implementation logs the exception at warn level,
+	 * <p>The default implementation logs the exception at {@code WARN} level,
 	 * not propagating it to the JMS provider &mdash; assuming that all handling of
 	 * acknowledgement and/or transactions is done by this listener container.
 	 * This can be overridden in subclasses.
@@ -916,7 +916,8 @@ protected void invokeExceptionListener(JMSException ex) {
 	}
 
 	/**
-	 * Invoke the registered ErrorHandler, if any. Log at warn level otherwise.
+	 * Invoke the registered {@link #getErrorHandler() ErrorHandler} if any.
+	 * Log at {@code WARN} level otherwise.
 	 * @param ex the uncaught error that arose during JMS processing
 	 * @see #setErrorHandler
 	 */