why sdxl_plus use StableDiffusionXLPipeline while sdxl_plus_face need a custom pipeline - StableDiffusionXLCustomPipeline

[machengcheng2016]

Hi @akk-123 , by checking the differences between StableDiffusionXLCustomPipeline and official StableDiffusionXLPipeline, i think the only thing matters is that StableDiffusionXLCustomPipeline utilizes control_guidance_start and control_guidance_end to decide which period of inference will I use image conditioning (here).