Issue 50818 - dsconf pwdpolicy get error
Description: When trying to retrieve a global or local policy we now see:
policyError: 'PwPolicyManager' object has no attribute 'get_attr_list'
Someone removed the function get_attr_list() along the way.
Added the same logic back, and improved it to only report attributes
that are set.
relates: https://pagure.io/389-ds-base/issue/50818
Reviewed by: spichugi(Thanks!)