GH-8654: Fix bean deps for messaging annotations (#8657)

Fixes #8654

Spring Framework has an ability to start dependant beans automatically
when we start the current one.

The `AbstractMethodAnnotationPostProcessor` is missing a bean dependency
registration causing errors in target applications when Messaging Annotations configuration is used.

* Add `registerDependentBean()` into an `AbstractMethodAnnotationPostProcessor` when we generate
and register a `ConsumerEndpointFactoryBean`
* Change one of the `ClientManagerBackToBackTests` configuration to rely on a `@ServiceActivator`
for `Mqttv5PahoMessageHandler` bean to ensure that change in the `AbstractMethodAnnotationPostProcessor`
has a proper effect

**Cherry-pick to `6.1.x` & `6.0.x`**

Author: artembilan

spring-integration-core/src/main/java/org/springframework/integration/config/AbstractMethodAnnotationPostProcessor.java

@@ -270,6 +270,7 @@ else if (reactive != null) {
 		String endpointBeanName =
 				generateHandlerBeanName(beanName, mergedAnnotations)
 						.replaceFirst("\\.(handler|source)$", "");
+		this.beanFactory.registerDependentBean(beanName, endpointBeanName);
 		this.definitionRegistry.registerBeanDefinition(endpointBeanName, endpointBeanDefinition);
 	}
 

spring-integration-mqtt/src/test/java/org/springframework/integration/mqtt/ClientManagerBackToBackTests.java

@@ -28,6 +28,7 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.event.EventListener;
+import org.springframework.integration.annotation.ServiceActivator;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
 import org.springframework.integration.mqtt.core.Mqttv3ClientManager;
@@ -195,8 +196,9 @@ public Mqttv5ClientManager mqttv5ClientManager() {
 		}
 
 		@Bean
-		public IntegrationFlow mqttOutFlow(Mqttv5ClientManager mqttv5ClientManager) {
-			return f -> f.handle(new Mqttv5PahoMessageHandler(mqttv5ClientManager));
+		@ServiceActivator(inputChannel = "mqttOutFlow.input")
+		public Mqttv5PahoMessageHandler mqttv5PahoMessageHandler(Mqttv5ClientManager mqttv5ClientManager) {
+			return new Mqttv5PahoMessageHandler(mqttv5ClientManager);
 		}
 
 		@Bean