Revert "Native Half on ARM (#119483)"
This reverts commit 8f3fd79b23d483e846537b62f49111696d117870.
Reverted https://github.com/pytorch/pytorch/pull/119483 on behalf of https://github.com/malfet due to Broke nightly arm builds (and will be breaking runtime), as F16 arithmetic is ARMv8.2 only, see https://github.com/pytorch/pytorch/actions/runs/8000968963/job/21851281141 ([comment](https://github.com/pytorch/pytorch/pull/119483#issuecomment-1959944948))
