Fix from_pretrained on torch 2.7: require torch>=2.8 for distributed checkpointing (#49652)
* Require torch>=2.8 for distributed checkpointing (hf_storage)
* Update distributed checkpoint error messages to torch>=2.8
* Update FSDP2/DCP torch floor in mixin to 2.8
* Add regression test for #49651
* Delete tests/utils/test_distributed_checkpoint_guard.py
Overkill!
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Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>
Co-authored-by: Anton Vlasjuk <73884904+vasqu@users.noreply.github.com>