Disable test_proper_exit flaky worker_kill (#22208)
Summary:
I learned from https://github.com/pytorch/pytorch/pull/22058 that `worker_kill` is just flaky, regardless of `hold_iter_reference`. So let's disable it altogether for now.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22208
Differential Revision: D15990307
Pulled By: soumith
fbshipit-source-id: d7d3f4fe7eaac4987f240cb8fd032c73a84157d7
