Revert "[export] Fix dict.get() to dict.setdefault() for param lookup. (#108587)"
This reverts commit c99a70c8dfc98dd5e6905990c41194c2ceb1318b.
Reverted https://github.com/pytorch/pytorch/pull/108587 on behalf of https://github.com/huydhn due to Sorry for reverting your change, but it is failing one internal test. Please take a look at the diff D48995555 for more details ([comment](https://github.com/pytorch/pytorch/pull/108587#issuecomment-1708933010))
