Revert D29928698: [pytorch][PR] Use private squid proxy
Test Plan: revert-hammer
Differential Revision:
D29928698 (https://github.com/pytorch/pytorch/commit/6da4a255091080bd9d3e748a497c8d95a4cddfeb)
Original commit changeset: 4ee78be0abe3
fbshipit-source-id: 44679a2b247ba8163f09895d9d36ecf5df4390b8
