Review package and property name for persistence exception translation auto-configuration

[wilkinsona]

Framework's PersistenceExceptionTranslationPostProcessor is in its spring-tx module in the org.springframework.dao.annotation package. In the restructured 4.0.x branch, auto-configuration for it is now in spring-boot-tx in the org.springframework.boot.transaction.autoconfigure package. The auto-configuration provides a single property, spring.dao.exceptiontranslation.enabled.