Revert "Test than subtypes (behaviors) provides field defaults."

This reverts commit cb1d39edc030b13d16a091ba44f05021ca57bbe6.
Revert "update changelog"

This reverts commit 42dc44f21068176dd79561fe3da69a5478c204f9.
Revert "Backport __getattr__ method from 2.x, this way we look for attrs into subtypes (behaviors) too."

This reverts commit 6371d7deeb2639d641c181a49c58808d0f378053.