suppress errors arising from deleting non-existent files during client uninstall
    
    When rolling back partially configured IPA client a number of OSErrors pop up
    due to uninstaller trying to remove files that do not exist anymore. This
    patch supresses these errors while keeping them in log as debug messages.
    
    https://fedorahosted.org/freeipa/ticket/4966
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>