[LLVM] Remove nuw neg (#86295)

This patch removes APIs that creating NUW neg. It is a trivial case
because `sub nuw 0, X` always gets simplified into zero.
I believe there is no optimization opportunities in the real-world
applications that we can take advantage of the nuw flag.

Motivated by
https://github.com/llvm/llvm-project/pull/84792#discussion_r1524891134.

Compile-time improvement:
https://llvm-compile-time-tracker.com/compare.php?from=d1f182c895728d89c5c3d198b133e212a5d9d4a3&to=da7b7478b7cbb32c09d760f6b8d0e67901e0d533&stat=instructions:u