Revert D33778917: Disable some forward mode AD tests
Test Plan: revert-hammer
Differential Revision:
D33778917 (https://github.com/pytorch/pytorch/commit/24f577dcb2f4e52647caf37bfb52608e19b989b8)
Original commit changeset: 57dfbff61817
Original Phabricator Diff: D33778917 (https://github.com/pytorch/pytorch/commit/24f577dcb2f4e52647caf37bfb52608e19b989b8)
fbshipit-source-id: f734169bc15baacbe40da904a84def02a1af8261
(cherry picked from commit 630edf5bedc3bd06c1da796e428e3d31d3b44bde)
