Fix SmartLifecycle.stop(Runnable) usage

* Also remove redundant `stop(Runnable)` implementations which repeat
 a `default` one in the `SmartLifecycle`

**Cherry-pick to 2.1.x & 2.0.x**

# Conflicts:
#	spring-rabbit/src/main/java/org/springframework/amqp/rabbit/core/BrokerEventListener.java
#	spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/RabbitListenerEndpointRegistry.java

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/config/ListenerContainerFactoryBean.java

@@ -629,6 +629,9 @@ public void stop(Runnable callback) {
 		if (this.container != null) {
 			this.container.stop(callback);
 		}
+		else {
+			callback.run();
+		}
 	}
 
 }

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

@@ -256,18 +256,23 @@ public void stop() {
 
 	@Override
 	public void stop(Runnable callback) {
-		Collection<MessageListenerContainer> listenerContainers = getListenerContainers();
-		AggregatingCallback aggregatingCallback = new AggregatingCallback(listenerContainers.size(), callback);
-		for (MessageListenerContainer listenerContainer : listenerContainers) {
-			try {
-				listenerContainer.stop(aggregatingCallback);
-			}
-			catch (Exception e) {
-				if (this.logger.isWarnEnabled()) {
-					this.logger.warn("Failed to stop listener container [" + listenerContainer + "]", e);
+		Collection<MessageListenerContainer> containers = getListenerContainers();
+		if (containers.size() > 0) {
+			AggregatingCallback aggregatingCallback = new AggregatingCallback(containers.size(), callback);
+			for (MessageListenerContainer listenerContainer : containers) {
+				try {
+					listenerContainer.stop(aggregatingCallback);
+				}
+				catch (Exception e) {
+					if (this.logger.isWarnEnabled()) {
+						this.logger.warn("Failed to stop listener container [" + listenerContainer + "]", e);
+					}
 				}
 			}
 		}
+		else {
+			callback.run();
+		}
 	}
 
 	@Override