Revert D19987020: [pytorch][PR] Add the sls tensor train op
Test Plan: revert-hammer
Differential Revision:
D19987020 (https://github.com/pytorch/pytorch/commit/f31b111a352dd9de5e432f137913a0f3c106eb9a)
Original commit changeset: e3ca7b00a374
fbshipit-source-id: a600c747a45dfb51e0882196e382a21ccaa7b989
