[PyTorch] Add TI::borrowing_nullary_op and use it (#58280)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58280
All core PyTorch uses of TensorIterator::nullary_op look like they can safely borrow.
ghstack-source-id: 129471193
Test Plan: Existing CI
Reviewed By: bhosmer
Differential Revision: D28429695
fbshipit-source-id: 404cf6db31e45e5cf7ae6d2f113c5a8eff6f7c3d
