[clean] remove unneeded validator, assigning class_, for GroupBase

Author: yhteoh

src/oqd_dataschema/base.py

@@ -74,15 +74,6 @@ def __init_subclass__(cls, **kwargs):
         # Auto-register new group types
         GroupRegistry.register(cls)
 
-    @model_validator(mode="before")
-    @classmethod
-    def auto_assign_class(cls, data):
-        if isinstance(data, BaseModel):
-            return data
-        if isinstance(data, dict):
-            data["class_"] = cls.__name__
-        return data
-
 
 class Dataset(BaseModel, extra="forbid"):
     """