authselect test: skip test if authselect is not available
Currently, the test is skipped if the platform is fedora-like. The
decision to skip should rather be based on authselect command
availability (i.e. when ipaplatform.paths.paths.AUTHSELECT is None).
Related to
https://pagure.io/freeipa/issue/7377
Reviewed-By: Christian Heimes <cheimes@redhat.com>