NH-3269 - Should not map base class properties by inherited class mapping

JIRA: https://nhibernate.jira.com/browse/NH-3269

Proposed fix breaks two test in `AllPropertiesRegistrationTests`:
-`WhenMapPropertiesInTheInheritedThenMapInBase`
-`WhenMapPropertiesInTheInheritedUsingMemberNameThenMapInBase`

But both tests sounds wierd for me