StoreMigrator ThreadLeak when calling SerializationConfigUtil::getMarshaller

Currently SerializationConfigUtil::getMarshaller leaks a thread because it creates a EmbeddedCacheManager in order to retrieve the PersistenceMarshallerImpl marshaller, but never closes the instance. Unfortunately, it's not as simple as just closing the EmbeddedCacheManager, because that will call stop on the PersistenceMarshallerImpl.