Restore LayerNorm numerics test (#64385)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64385
It was deleted in https://github.com/pytorch/pytorch/pull/63276.
The numerics test was meant to check LayerNorm behavior on large inputs,
but we deleted it without realizing that.
Test Plan: - wait for tests.
Reviewed By: ngimel
Differential Revision: D30702950
Pulled By: zou3519
fbshipit-source-id: a480e26c45ec38fb628938b70416cdb22d976a46
