fft: Increase tolerance for nd-fft tests (#57576)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/56820
The test only fails for inverse n-dim functions with `norm="forward"`. The relative error for isn't actually any bigger than other norm modes though. It's just that the magnitude of the result is bigger, so the absolute tolerance is less relative each element. So, I just increase the relative tolerance to compensate.
This `precisionOverride` is already applied to `fftn` and `rfftn` for exactly the same reason.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/57576
Reviewed By: albanD
Differential Revision: D28249222
Pulled By: mruberry
fbshipit-source-id: 734c7c1ae8236b253d6e3cd2218c05d21901c567
