Fix sort for slow gradcheck (#57192)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/57166
Generate new inputs until we get one where we know that x + eps won't change its sorted order.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/57192
Reviewed By: albanD
Differential Revision: D28102361
Pulled By: soulitzer
fbshipit-source-id: a12377cc135b0bd92adf0914a100969317b97e8c
