Previously, when health probes were enabled, the post-processor of
AutoConfiguredHealthEndpointGroups resulted in the bean no longer
implementing AdditionalPathMapper. This then caused a
ClassCastException when working with AdditionalPathMapper beans
in EndpointRequest's additional path mapping support.
This commit updates the type returned by the post-processor to
implement both HealthEndpointGroups and AdditionalPathMapper, as
AutoConfiguredHealthEndpointGroups does. Its implementation of
getAdditionalPaths produces a result that combines both the
additional paths of the original HealthEndpointGroups bean and its
own additional paths for the probes.
Fixes gh-44052