Remove validateBlock method
Remove validateBlock method

Related to https://github.com/sonata-project/SonataAdminBundle/pull/2792

If this change is ok, I can submit others PRs for Routing and Block bundles as well.

sonata-project/SonataDoctrinePhpcrAdminBundle,sonata-project/SonataDoctrinePhpcrAdminBundle,sonata-project/SonataDoctrinePhpcrAdminBundle