tests: use errno.EBADF instead of hardcoded number in _close_file() (GH-148345)

test_interpreters: use errno.EBADF instead of hardcoded number in _close_file()

Replace the hardcoded `9` check in `Lib/test/test_interpreters/utils.py` with `errno.EBADF`.

Using `errno.EBADF` makes the helper portable across platforms with different errno numbering while preserving the intended behavior.