Schema initialization now happens in @PostConstruct (effectively)
whether it is via the Hibernate EntityManagerFactory or the
Boot DataSourceInitialization (in addition or instead). The data.sql
script if it exists is still executed on an event fired from the
other places, so those tests are passing.

Flyway and liquibase have bean factory post processors (like
the one they use to order the audit aspect in Spring Data) that
enforce a dependency on those components from the EntityManagerFactory.
So Hibernate validation is still happy (and there are 2 tests to
prove it now as well).

Fixes gh-1022