Removed formal deprecation warnings for AbstractSingletonFactoryBean and
its TransactionProxyFactoryBean and CacheProxyFactoryBean subclasses.
This is principally because TPFB is still used by Grails and could
conceivably be used to good effect by any third-party framework in a
similar fashion. CPFB is new with 3.1, but similar use is predictable.
Deprecations have been replaced by strong recommendations that users
avoid these types in modern Spring applications and favor the use of
namespaces and annotatinos, such as tx: and @Transactional (around
since Spring 2.x) and cache: and @Cacheable.
Issue: SPR-8680, SPR-8686