Command-a-vision fix
Author: dongluw
Pull request: yes

# What does this PR do?
- fix a bug in the image resize code, which affects performance
before fix:
<img width="512" height="512" alt="patch_01" src="https://github.com/user-attachments/assets/baf30355-8f3a-4785-aeef-7864ba8d7e28" />

after fix:
<img width="512" height="512" alt="patch_1" src="https://github.com/user-attachments/assets/9757b38b-8faa-49a1-8b51-7447797a4d9f" />

- add test cases
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Fixes # (issue)


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Comments:
cc @molbap @yonigozlan @zucchini-nlp 

Hi @dongluw , thanks for the contribution, indeed there seems to be a flip issue. however how do you obtain the test image above? I'm surprised our tests haven't caught this, it should be all wrong, so a reproducer would help

hey @molbap I saved the `stacked_images` to images patch by patch https://github.com/dongluw/transformers/blob/9ef13ef775fe5a05c634fb2705a500ef59f28763/src/transformers/models/cohere2_vision/image_processing_cohere2_vision_fast.py#L228

this issue only affects generation quality if images are of very high/low aspect ratio

full image is 
![output_image17](https://github.com/user-attachments/assets/0ecb88e9-4cee-4ea3-b1c5-5142c816739a)



**[For maintainers]** Suggested jobs to run (before merge)

run-slow: cohere2_vision

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