tests: do not include t_client.sh in dist

tests: do not include t_client.sh in dist

It is generated from t_client.sh.in by configure,
so no need to ship it. Due to the dependency on
the configuration it also might break reproducibility
of the dist tarball.

Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20230418134941.86637-1-frank@lichtenheld.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26596.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>