Remove some unnecessary python functional wrappers (#61608)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61608
See #61544 for an example of issues created by functional wrappers. In this
case, these are directly wrapping the native function with no added
functionality. One exception was `bilinear` which was just missing the default
argument in C++, but was otherwise the same.
I've kept the symbol `torch.functional.istft` because it looks like public API,
but it could just as easily be moved to `_torch_docs.py`.
Test Plan: Imported from OSS
Reviewed By: ngimel
Differential Revision: D31401361
Pulled By: albanD
fbshipit-source-id: 162b74d0b2d4f2e5c4834687a94541960cefdd52
(cherry picked from commit 700cd73ca121d903f04f539af171d3f768565921)
