Revert "Mount /etc/hosts into container (#100475)"
This reverts commit 99ded8bbcea896b02f1c0babb055329c503ca95e.
Reverted https://github.com/pytorch/pytorch/pull/100475 on behalf of https://github.com/malfet due to Breaks distributed tests ([comment](https://github.com/pytorch/pytorch/pull/100475#issuecomment-1532097309))
