[refactor] enhance readability of flux related pipelines

[Luciennnnnnn]

What does this PR do?

This PR refactors the FLUX-related pipelines to improve clarity and consistency, particularly in regards to height and width determination. The changes align the implementation more closely with other pipelines in the library, enhancing overall code coherence and maintainability.

The original code obscured the details of how latents packing affects resolution, but this change makes the process more transparent and easier to understand.

@yiyixuxu @asomoza

[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.

[DN6]

Nice clean up! 👍🏽

[yiyixuxu]

@Luciennnnnnn can you run make style and make fix-copies?

[Luciennnnnnn]

@Luciennnnnnn can you run make style and make fix-copies?

Sure! This is my first contribution to diffusers, i'll try it

[Luciennnnnnn]

@Luciennnnnnn can you run make style and make fix-copies?

Done!

[Luciennnnnnn]

The previous commit is failed on two checks, after modification, how to rerun checks

[Luciennnnnnn]

Hi @yiyixuxu , I see checks failed on FLUX training examples, which is not related to my PR. How can I pass it?

[yiyixuxu]

Hi @Luciennnnnnn thanks for the PR! It is a really nice PR
these failures are actually related to the PR. You did not "break" the training examples! but because they were using some of the pipeline methods/ config/logic that we changed, we will need to update them too for example here

diffusers/examples/dreambooth/train_dreambooth_flux.py

Line 1543 in 24c7d57

vae_scale_factor = 2 ** (len(vae.config.block_out_channels))

Would you be interested in working on that? If not, I can take over when I have a little bit more time:)

[Luciennnnnnn]

@yiyixuxu

Would you be interested in working on that?

Sure! I have updated training example accordingly.

[yiyixuxu]

Thanks @Luciennnnnnn
really nice job:) hope to see more of your PRs soon