Revert "fix: Make Recipe.model_dump() output compatible .... (#1378)

This PR reverts commit 998be99 which
was merged prematurely. The required base tests were skipped during the
original review process. When these tests eventually ran on the main
branch, they revealed a failure:


https://github.com/vllm-project/llm-compressor/actions/runs/14628792870/job/41046641641

The original PR #1328 has been reopened to address the identified issues
before resubmitting.

Author: rahul-tuli

src/llmcompressor/recipe/recipe.py

@@ -46,7 +46,7 @@ def from_modifiers(
 
         (Note: all modifiers are wrapped into a single stage
         with the modifier_group_name as the stage name. If modifier_group_name is None,
-        the default run_type is `oneshot`)
+        the default run type is `oneshot`)
 
         Lfecycle:
         | - Validate Modifiers
@@ -524,33 +524,6 @@ def dict(self, *args, **kwargs) -> Dict[str, Any]:
 
         return dict_
 
-    def model_dump(self, *args, **kwargs) -> Dict[str, Any]:
-        """
-        Override the model_dump method to provide a dictionary representation that
-        is compatible with model_validate.
-
-        Unlike the standard model_dump, this transforms the stages list to a format
-        expected by the validation logic, ensuring round-trip compatibility with
-        model_validate.
-
-        :return: A dictionary representation of the recipe compatible with
-            model_validate
-        """
-        # Get the base dictionary from parent class
-        base_dict = super().model_dump(*args, **kwargs)
-
-        # Transform stages into the expected format
-        if "stages" in base_dict:
-            stages_dict = {}
-            for stage in base_dict["stages"]:
-                group = stage["group"]
-                if group not in stages_dict:
-                    stages_dict[group] = []
-                stages_dict[group].append(stage)
-            base_dict["stages"] = stages_dict
-
-        return base_dict
-
     def yaml(self, file_path: Optional[str] = None) -> str:
         """
         Return a yaml string representation of the recipe.