INT-3538-2: `RoutingSlipHeaderValueMessageProcessor` improvement

Since `HeaderEnricher` populates `beanFactory` to its `HeaderValueMessageProcessor`s,
there is no reason to specify `RoutingSlipHeaderValueMessageProcessor` as a separate bean.
Therefore the `IntegrationEvaluationContextAware` may not be reached.
Remove its support from `RoutingSlipHeaderValueMessageProcessor` and just rely on the `setBeanFactory`