Revert D33178977: [bc-breaking][quant][be] Refactor fuser_method to include `is_qat` argument
Test Plan: revert-hammer
Differential Revision:
D33178977 (https://github.com/pytorch/pytorch/commit/ef501e8fed694bf7218ec1577d5873e0717ca18a)
Original commit changeset: 0c1499c45526
Original Phabricator Diff: D33178977 (https://github.com/pytorch/pytorch/commit/ef501e8fed694bf7218ec1577d5873e0717ca18a)
fbshipit-source-id: f3912e210e8c588fdbdc9c3c5f4acf2aa8fe6678
(cherry picked from commit cd62183414e757b6012522aee01442e818b7b06d)
