Revert D34034847: DispatchKeySet perf improvements
Test Plan: revert-hammer
Differential Revision:
D34034847 (https://github.com/pytorch/pytorch/commit/8aa3620d73d9afcdbcf3d691cdd45ae05ec5e7d5)
Original commit changeset: a930e44513a7
Original Phabricator Diff: D34034847 (https://github.com/pytorch/pytorch/commit/8aa3620d73d9afcdbcf3d691cdd45ae05ec5e7d5)
fbshipit-source-id: 57b8b7dee252bb8d10316189a034517a28c42199
(cherry picked from commit c3151d4e73836cdfcca37f222a086d2e00755601)
