Fix Flux2ImageProcessor AttributeError in train_dreambooth_lora_flux2…

[knd0331]

…_img2img.py

The training script incorrectly accessed Flux2ImageProcessor.image_processor which doesn't exist as a class attribute, causing AttributeError when running Flux2 img2img DreamBooth training.

Changes:

• Initialize Flux2ImageProcessor instance in DreamBoothDataset.init
• Replace incorrect class attribute access with instance method calls

Fixes #12778

What does this PR do?

Title:
Fix Flux2ImageProcessor AttributeError in train_dreambooth_lora_flux2_img2img.py

Body:

Summary

Fix AttributeError: type object 'Flux2ImageProcessor' has no attribute 'image_processor' when
running Flux2 img2img DreamBooth training script.

Problem

The training script incorrectly accesses Flux2ImageProcessor.image_processor which doesn't exist as
a class attribute.

Solution

Initialize Flux2ImageProcessor instance in DreamBoothDataset.__init__ and use instance methods.

Changes

• Initialize Flux2ImageProcessor instance in DreamBoothDataset.__init__
• Replace incorrect class attribute access with instance method calls

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