Rework the logic around `ManagedList` in the `DefaultConfiguringBeanFactoryPostProcessor`
when it registers a `IntegrationContextUtils.MESSAGE_HANDLER_FACTORY_BEAN_NAME` and
`IntegrationContextUtils.LIST_MESSAGE_HANDLER_FACTORY_BEAN_NAME` into a dedicated
`MessageHandlerMethodFactoryCreatingFactoryBean` with pure Java code instead of
`BeanDefinition` burden
* Deprecate `IntegrationContextUtils.DISPOSABLES_BEAN_NAME` constant for
already removed internal bean
* Align JVM args for Gradle with Java 17 on the `6.0` branch
8c85fc9957