Fix model saving bug post training with tensor parallel

[bursteratom]

What does this PR do?

Currently, attempting to save model after training with tensor parallel gives the RuntimeError: Attempted to access the data pointer on an invalid python storage, this is due to the state dict not properly gathered from the sharded tensors beforehand. This PR fixes the error, allowing for successful model saving.

Big thank you to @SalmanMohammadi for the discussion!

Fixes # (issue)
#34194 (comment)
#36436

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[bursteratom]

@kmehant Wondering what your thoughts are?