Fix wrong `do_classifier_free_guidance` threshold in ZImagePipeline #36869

Job	Run time
check_code_quality	31s
check_repository_consistency	32s
Hub tests for models, schedulers, and pipelines	1m 42s
Fast PyTorch Models & Schedulers CPU tests	7m 56s
Fast PyTorch Pipeline CPU tests	16m 52s
PyTorch Example CPU tests	19m 3s
LoRA tests with PEFT main	10m 11s
	56m 47s

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