httpinstance: clean up /etc/httpd/alias on uninstall
    
    Restore cert8.db, key3.db, pwdfile.txt and secmod.db in /etc/httpd/alias
    from backup on uninstall.
    
    Files modified by IPA are kept with .ipasave suffix.
    
    https://pagure.io/freeipa/issue/4639
    
    Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>