Difference in _use_fd_functions in shutil.py and test_shutil.py

Bug report

Bug description:

When switching from os.listdir to os.scandir 7 years ago somebody forgot to update the definition of _use_fd_functions in test_shutil together with shutil module.

in shutil:

_use_fd_functions = ({os.open, os.stat, os.unlink, os.rmdir} <=
                     os.supports_dir_fd and
                     os.scandir in os.supports_fd and
                     os.stat in os.supports_follow_symlinks)

in test_shutil:

        _use_fd_functions = ({os.open, os.stat, os.unlink, os.rmdir} <=
                             os.supports_dir_fd and
                             os.listdir in os.supports_fd and
                             os.stat in os.supports_follow_symlinks)

I believe there is no need to calculate this variable twice so I'm gonna propose a PR where I use the value from shutil.py in its tests. Nobody will ever forget to update both places again.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Inizia confrontando le definizioni di _use_fd_functions in shutil.py e test_shutil.py, quindi esamina come viene utilizzato il valore lato test. Esegui i test di shutil per confermare il comportamento attuale e verifica che i test utilizzino l'unico valore del modulo senza modificare la copertura o il comportamento specifico della piattaforma.