GH-2511: Fix Container Stop Regression

Resolves #2511

When inactive containers are present, the `DefaultLifecycleProcessor` hangs
for (default) 30 seconds waiting for containers to stop.

When `stop(Runnable)` is called, the callback was not run if the container
was not running; this was a regression caused by 1fdfe65.

**cherry-pick to 2.4.x**

(cherry picked from commit 52d8ce5)

Author: garyrussell

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

@@ -1367,6 +1367,9 @@ public void shutdown(@Nullable Runnable callback) {
 			if (!isActive()) {
 				logger.debug("Shutdown ignored - container is not active already");
 				this.lifecycleMonitor.notifyAll();
+				if (callback != null) {
+					callback.run();
+				}
 				return;
 			}
 			this.active = false;