Fix get_distribution for Alpine Linux (#17224)
Fix get_distribution for Alpine Linux (#17224)

To override a generic class that is subclassed based on platform, the
subclass must define platform and distribution.

The load_platform_subclass() calls the get_platform() and
get_distribution() methods to detect the platform and the distribution.

On Alpine Linux, get_distribution() method returns None and it is not
possible to have different implementations based on detected platform.
thaim/ansible,thaim/ansible