Align VideoLlavaProcessor with Transformers v4.51.3

[yafshar]

The GaudiVideoLlavaProcessor has been removed from optimum-habana as its functionality is now fully aligned with the v4.51.3 Transformers implementation. No custom logic is required, and maintaining a separate class is redundant.

Update GaudiVideoLlavaForConditionalGeneration implementation with the v4.51.3 transformers changes while retaining token_idx argument for compatibility with Gaudi optimizations.

>>> python -m pytest tests/test_image_to_text_example.py -k llava
================= 7 passed, 7 deselected in 704.09s (0:11:44) ==================

>>> python -m pytest tests/test_video_llava.py
======================== 1 passed in 109.60s (0:01:49) =========================

The masked_scatter is not a bottleneck on G3 anymore.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?

[yafshar]

@regisss can you please label this PR for synapse 1.22

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[yafshar]

@astachowiczhabana I will close this PR and open #2129 with the new base of v1.19-release