CachedIntrospectionResults and co consistently avoid synchronization (through use of ConcurrentReferenceHashMap)

As a side effect, through ConcurrentReferenceHashMap, we're using soft references for non-cache-safe bean classes.

Issue: SPR-11867
AbstractAutowireCapableBeanFactory's createBean/autowireBean/configureBean use CacheUtils.isCacheSafe to re-enable PropertyDescriptor caching

Issue: SPR-11875