Revert "conv-bn folding in low precision (#106576)"
This reverts commit c21df02ec0b9fd366bdf203134595664de030758.
Reverted https://github.com/pytorch/pytorch/pull/106576 on behalf of https://github.com/kit1980 due to breaking internal builds, see D48144191 ([comment](https://github.com/pytorch/pytorch/pull/106576#issuecomment-1670768310))
