refactor(magic_pdf): remove unnecessary comment

- Remove commented-out call to clean_memory() function
- This change simplifies the code by eliminating an unused code snippet

magic_pdf/pdf_parse_union_core_v2.py

@@ -825,7 +825,7 @@ def pdf_parse_union(
         'pdf_info': pdf_info_list,
     }
 
-    # clean_memory()
+    clean_memory()
 
     return new_pdf_info_dict