Add data_parallel_size to VllmConfig string representation (#24298)

Co-authored-by: Cong Chen <congc@meta.com>

vllm/config/__init__.py

@@ -3790,6 +3790,7 @@ class VllmConfig:
             f"load_format={self.load_config.load_format}, "
             f"tensor_parallel_size={self.parallel_config.tensor_parallel_size}, "  # noqa
             f"pipeline_parallel_size={self.parallel_config.pipeline_parallel_size}, "  # noqa
+            f"data_parallel_size={self.parallel_config.data_parallel_size}, "  # noqa
             f"disable_custom_all_reduce={self.parallel_config.disable_custom_all_reduce}, "  # noqa
             f"quantization={self.model_config.quantization}, "
             f"enforce_eager={self.model_config.enforce_eager}, "