Bug: _onload_from_disk reads safetensors file twice when stream=None in group offloading

[gagandhakrey]

This is the issue that used to be in the huggingface/diffusers , same is used here , i have fixed it there
PR for the same : huggingface/diffusers#13851 , please merge same change here also

[gagandhakrey]

raised pr here for the same
#3