Revert "ExportedProgram.transform now updates graph_signature automatically (#107080)"
This reverts commit 8c9b2fe8f097cd4b32000e5124232a0047d92234.
Reverted https://github.com/pytorch/pytorch/pull/107080 on behalf of https://github.com/izaitsevfb due to Breaks executorch tests, see D48333170 ([comment](https://github.com/pytorch/pytorch/pull/107080#issuecomment-1679588292))
