[Polish CustomOP] Clean custom OP output when import modules (#51125)

Author: jiahy0825

python/paddle/utils/cpp_extension/extension_utils.py

@@ -190,7 +190,6 @@ def __bootstrap__():
                     assert isinstance(spec.loader, importlib.abc.Loader)
                     spec.loader.exec_module(mod)
                 except ImportError:
-                    print('using custom operator only')
                     mod = types.ModuleType(__name__)
 
             # load custom op shared library with abs path