[FSDP] Clarify loss dtype check in `_test_fsdp_parity` (#90251)
A recent PR deprecated `torch.testing.assert_allclose` in favor of `torch.testing.assert_close` and left a `TODO`. This PR follows up to confirm that we do intend to have `check_dtype=False`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/90251
Approved by: https://github.com/rohan-varma
