Remove ref to test_distributed_fork (#64197)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64197
Removes this line as test is gone.
ghstack-source-id: 136986275
Test Plan: CI
Reviewed By: walterddr
Differential Revision: D30642929
fbshipit-source-id: a0c7dfdfb35a4a7f7ec1b881dbea53d85136012c