Turn @config into a dataclass_transform (#31541)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/config/parallel.py

@@ -3,12 +3,10 @@
 
 import os
 from collections.abc import Callable
-from dataclasses import replace
 from typing import TYPE_CHECKING, Any, Literal
 
 import torch
 from pydantic import Field, field_validator, model_validator
-from pydantic.dataclasses import dataclass
 from torch.distributed import ProcessGroup, ReduceOp
 from typing_extensions import Self
 
@@ -50,7 +48,6 @@ All2AllBackend = Literal[
 
 
 @config
-@dataclass
 class EPLBConfig:
     """Configuration for Expert Parallel Load Balancing (EP)."""
 
@@ -94,7 +91,6 @@ class EPLBConfig:
 
 
 @config
-@dataclass
 class ParallelConfig:
     """Configuration for the distributed execution."""
 
@@ -715,6 +711,3 @@ class ParallelConfig:
             )
 
         return self
-
-    def replace(self, **kwargs) -> Self:
-        return replace(self, **kwargs)