Remove old Travis CI related files

Remove old Travis CI related files

They are not used or mainained anymore. So just remove them.

Change-Id: I704f7c9a9fe9a2b988410c4586183302392e690d
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20230707144628.378541-1-frank@lichtenheld.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26834.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit fd43636c417b479e95ca9f3eca6b90c410bc7686)