Don't implement AutoClosable on AudienceProvider

[kezz]

This makes IDEs and other linting tools nag at you for not using try-with-resources and for not closing it. It's not really necessary nor particularly useful in this case for it to exist. It also gives the impression that the audience providers should be used like other AutoClosable objects, like database connections or input streams (where you spin one up, use it and close it) which is not the case.