fix upgrade: wait for proper DS socket after DS restart
DS restart executed by upgrade plugin causes that upgrade framework
is waiting for the improper socket. It leads to TimeoutError because
DS is not listening on 389 port during upgrade. This commit fixes the issue.
Required for: https://fedorahosted.org/freeipa/ticket/5665
Reviewed-By: Alexander Bokovoy <email@example.com>
Reviewed-By: Tomas Babej <firstname.lastname@example.org>