Use NSS for name->resolution in IPA installer
    
    This fixes scenarios where IPA server is not able to resolve own name
    and option --ip-address was not specified by the user.
    
    This partially reverts changes from commit
    dc405005f537cf278fd6ddfe6b87060bd13d9a67
    
    https://fedorahosted.org/freeipa/ticket/5962
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>