Update pipeline_flux_img2img.py to add missing vae_slicing and vae_tiling calls.

[Meatfucker]

Adds missing vae_slicing and vae_tiling calls to FluxImage2ImagePipeline

What does this PR do?

Fixes # (issue)

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[asomoza]

thanks, left some comments

[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.

[asomoza]

thanks a lot!