Revert D29892919: Add squid proxy as egress cache
Test Plan: revert-hammer
Differential Revision:
D29892919 (https://github.com/pytorch/pytorch/commit/e63160d7359f319b20b6cf5c9bb7c0205766aa9c)
Original commit changeset: ac17227f2553
fbshipit-source-id: b78313147d60f26c1df68a25293e6b571ba66919
