Ensure that Jandex indexes are released from JPA deployment memory after deployment completes

org.jboss.as.jpa.service.PersistenceUnitServiceImpl#start() needs to always call pu.setAnnotationIndex(null) to clear the deployment reference to the Jandex Indexes.

Currently without the fix, the Jandex Index will be released at application undeployment time. With the fix, the Jandex Index memory will be released after application deployment is complete. Note that the Jandex Index contains metadata for the application deployment classes and are not needed after deployment is complete.

Note that this problem shouldn't occur when persistence.xml contains:

<property name="wildfly.jpa.twophasebootstrap" value="false"/>