GH-8697: No autowire for Int ConversionService

Fixes #8697

The `IntegrationUtils.INTEGRATION_CONVERSION_SERVICE_BEAN_NAME` is not designed
for end-user code autowire, rather internal framework requirement

* Mark `BeanDefinition` for `IntegrationUtils.INTEGRATION_CONVERSION_SERVICE_BEAN_NAME`
as `setAutowireCandidate(false)`

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

@@ -65,10 +65,11 @@ public void initialize(ConfigurableListableBeanFactory beanFactory) throws Beans
 		}
 
 		if (!registry.containsBeanDefinition(IntegrationUtils.INTEGRATION_CONVERSION_SERVICE_BEAN_NAME)) {
+			RootBeanDefinition beanDefinition = new RootBeanDefinition(CustomConversionServiceFactoryBean.class);
+			beanDefinition.setAutowireCandidate(false);
 			registry.registerBeanDefinition(IntegrationUtils.INTEGRATION_CONVERSION_SERVICE_BEAN_NAME,
-					new RootBeanDefinition(CustomConversionServiceFactoryBean.class));
+					beanDefinition);
 		}
-
 	}
 
 	private static boolean isIntegrationConverter(BeanDefinition beanDefinition) {