GH-2741: SMLC: Release consumer after its main loop

Fixes: #2741

Apparently the consumer might be in the cancelled state,
so `this.activeObjectCounter.release(this);` in the `BlockingQueueConsumer.nextMessage()` is not reachable.

(cherry picked from commit 52b68ba)

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

@@ -1396,6 +1396,7 @@ public void run() { // NOSONAR - line count
 				}
 			}
 			finally {
+				SimpleMessageListenerContainer.this.cancellationLock.release(this.consumer);
 				if (getTransactionManager() != null) {
 					ConsumerChannelRegistry.unRegisterConsumerChannel();
 				}