Fix the incorrect output of sdxl inpaint

[yuanwu2017]

What does this PR do?

Fix the incorrect output of sdxl inpaint.
Command:
python text_to_image_generation.py --model_name_or_path diffusers/stable-diffusion-xl-1.0-inpainting-0.1 --base_image https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/diffusers/inpaint.png --mask_image https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/diffusers/inpaint_mask.png --prompts "concept art digital painting of an elven castle, inspired by lord of the rings, highly detailed, 8k" --seed 42 --scheduler euler_discrete --num_images_per_prompt 12 --batch_size 4 --image_save_dir ./xl2 --use_habana --use_hpu_graphs --gaudi_config Habana/stable-diffusion --sdp_on_bf16 --bf16

Before:

Images(only attach first four images ):

After：

Images(only attach first four images ):

Seeing from the results, the performance has no decline. The output pictures are more fine

Fixes # (issue)

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?

[yuanwu2017]

@regisss @dsocek Please help to review.

[yuanwu2017]

pass ci test.

[dsocek]

@yuanwu2017 did you test other schedulers? (e.g. default)? Also, did you try different seeds, prompts to really see that scheduler visually impairs images if we call set_begin_index vs. if we do not

[dsocek]

Please run more tests and show proof that we can safely remove this. For default scheduler removing this may cause issues. Also, can we do a larger sweep of prompts/seeds to justify removal

[dsocek]

@regisss Checked old jira info. We were getting error when using init_step_index without setting set_begin_index first (for ddim scheduler). This was around SW stack 1.16/1.17 and SDXL. I just did some tests on my side with 1.19 and seems this issue is not present anymore. @yuanwu2017 can you also test this? If this is the case, we can remove the set_begin_index if it improves visual quality in inpainting

[dsocek]

Update: @yuanwu2017 I tested 1.19 with all schedulers and the issue we saw in older releases is not showing. I also did observe better details in generated images, so I think it is safe to remove set_begin_index code. @yuanwu2017 could you also remove from other 3 SDXL pipelines in this PR? Thanks!

[yuanwu2017]

Update: @yuanwu2017 I tested 1.19 with all schedulers and the issue we saw in older releases is not showing. I also did observe better details in generated images, so I think it is safe to remove set_begin_index code. @yuanwu2017 could you also remove from other 3 SDXL pipelines in this PR? Thanks!

Ok. I will remove. Thanks.

[HuggingFaceDocBuilderDev]

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[regisss]

LGTM!