Revert "Add scalar conversion using avx instructions for half (#102140)"
This reverts commit 1d6a44656755c89f4f9a878865dcb0ac39af9a74.
Reverted https://github.com/pytorch/pytorch/pull/102140 on behalf of https://github.com/ZainRizvi due to Sorry, this is still breaking internal builds. Specifically, the dynamo test test_repros.py::DynamicShapesReproTests::test_odict_get_item_index_name ([comment](https://github.com/pytorch/pytorch/pull/102140#issuecomment-1686684117))
