Back out "[pytorch][PR] The dimension being reduced should not be coalesced by TensorIterator" (#47642)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47642
Original commit changeset: 02bb2b15694c
Test Plan: Covered by CI tests
Reviewed By: anjali411
Differential Revision: D24849072
fbshipit-source-id: a8790cbf46936aee7a6f504dac8595997175fc65
