[difusion] CI: speed up multimodal_gen ci (#13665)

Co-authored-by: Mick <mickjagger19@icloud.com>

python/sglang/multimodal_gen/configs/sample/base.py

@@ -413,9 +413,6 @@ class SamplingParams:
         if user_params is None:
             return
 
-        # Get fields defined directly in the subclass (not inherited)
-        subclass_defined_fields = set(type(self).__annotations__.keys())
-
         # Compare against current instance to avoid constructing a default instance
         default_params = SamplingParams()
 
@@ -432,7 +429,7 @@ class SamplingParams:
                 if field_name != "output_file_name"
                 else user_params.output_file_path is not None
             )
-            if is_user_modified and field_name not in subclass_defined_fields:
+            if is_user_modified:
                 if hasattr(self, field_name):
                     setattr(self, field_name, user_value)