Fix drop path being ignored in DINOv2
Author: fepegar
Pull request: yes

# What does this PR do?

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A `drop_path_rate` parameter exists in the DINOv2 model, which is propagated all the way to the DINOv2 layers, but never used. This PR addresses this by using the drop path layers in the `forward` pass of the DINOv2 layers, and removing an (I think) unnecessary extra instantiation.

Fixes #29140.


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## Who can review?

@amyeroberts @NielsRogge @molbap

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Comments:
Thanks for reviewing, @amyeroberts!