* INT-4517: Refactor beans in IntegrationRegistrar
JIRA: https://jira.spring.io/browse/INT-4517
The `IntegrationRegistrar` populates beans into the application context
too early and when the `allowBeanDefinitionsOverride` is disabled we
end up with the `BeanDefinitionOverrideException` just because end-user
beans are applied later.
* Move most of the bean definitions which can be overridden in the target
application from the `IntegrationRegistrar` into the
`DefaultConfiguringBeanFactoryPostProcessor`
* Revise their registration logic to be sure that some of them are
registered only once in the parent context nad others are registered
in the child context as well
* Refactor a `DslIntegrationConfigurationInitializer` do not register
an `IntegrationFlowDefinition.ReplyProducerCleaner` in the child context
one more time: it doesn't bring any local store within the current
child context
* Introduce a `NoBeansOverrideAnnotationConfigContextLoader` in tests
to ensure that in some test-cases we disallow an
`allowBeanDefinitionsOverride` as it is now in Spring Boot since it is
enabled by default in the Spring Framework
* Revernt DslIntegrationConfigurationInitializer changes
Regsiter all the required infrastructure beans in all the application
contexts to avoid class loader issue for `static` store access
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