Revert D31206837: [pytorch][PR] `*_solve` methods: implements forward AD
Test Plan: revert-hammer
Differential Revision:
D31206837 (https://github.com/pytorch/pytorch/commit/26e31f76b0a6257d40b8dbcd7fe393acea49f988)
Original commit changeset: 040beda97442
fbshipit-source-id: f28091327357af9f54f367eda6606240924b93ac
