[SD3] Fix mis-matched shape when num_images_per_prompt > 1 using without T5 (text_encoder_3=None) (#8558)
* fix shape mismatch when num_images_per_prompt > 1 and text_encoder_3=None
* style
* fix copies
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Co-authored-by: YiYi Xu <yixu310@gmail.com>
Co-authored-by: yiyixuxu <yixu310@gmail,com>