GH-1452: Close Connection in checkMissingQueues

Resolves #1452

While not a problem with connection factories provided by the framework
(which all ignore `close()`) the code should properly close the connection
after use.

**cherry-pick to 2.4.x, 2.3.x**

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/BlockingQueueConsumer.java

@@ -554,7 +554,8 @@ private void checkMissingQueues() {
  Connection connection = null; // NOSONAR - RabbitUtils
  Channel channelForCheck = null;
  try {
- channelForCheck = this.connectionFactory.createConnection().createChannel(false);
+ connection = this.connectionFactory.createConnection();
+ channelForCheck = connection.createChannel(false);
  channelForCheck.queueDeclarePassive(queueToCheck);
  if (logger.isInfoEnabled()) {
  logger.info("Queue '" + queueToCheck + "' is now available");