Make AtomicReferenceFieldUpdater fields static for [better performance](https://shipilev.net/blog/2015/faster-atomic-fu/#:~:text=thrown%20out%20of%20the%20window).

Make AtomicReferenceFieldUpdater fields static for [better performance](https://shipilev.net/blog/2015/faster-atomic-fu/#:~:text=thrown%20out%20of%20the%20window). #4163