Revert "Multiprocessing support for NT (#110292)"
This reverts commit f17fe89e14ef7c29690d989c857ae011b8589b80.
Reverted https://github.com/pytorch/pytorch/pull/110292 on behalf of https://github.com/kit1980 due to Causes CUDA memory leaks ([comment](https://github.com/pytorch/pytorch/pull/110292#issuecomment-1749852095))
