fix(file upload): correct upload method key for image config (#9568)

api/core/app/app_config/features/file_upload/manager.py

         file_upload_dict = config.get("file_upload")
         if file_upload_dict:
             if file_upload_dict.get("enabled"):
+                transform_methods = file_upload_dict.get("allowed_file_upload_methods") or file_upload_dict.get(
+                    "allowed_upload_methods", []
+                )
                 data = {
                     "image_config": {
                         "number_limits": file_upload_dict["number_limits"],
-                        "transfer_methods": file_upload_dict["allowed_upload_methods"],
+                        "transfer_methods": transform_methods,
                     }
                 }