Revert D29104396: Port `argmin` kernel to structured kernels.
Test Plan: revert-hammer
Differential Revision:
D29104396 (https://github.com/pytorch/pytorch/commit/226d745a0bf6ba174a08b92659613f4174aa393a)
Original commit changeset: 39c59bcc0446
fbshipit-source-id: 82de26f925a885f65572a785fa45a9980d3a974b
