gh-98415: Fix uuid.getnode() ifconfig implementation (#98423)

The uuid.getnode() function has multiple implementations, tested sequentially.
The ifconfig implementation was incorrect and always failed: fix it.

In practice, functions of libuuid library are preferred, if available:
uuid_generate_time_safe(), uuid_create() or uuid_generate_time().

Co-authored-by: Dong-hee Na <donghee.na92@gmail.com>