GHA: do not trigger builds in openvpn-build anymore

GHA: do not trigger builds in openvpn-build anymore

We do this via explicit PRs now, generated by renovate.
This allows much better control over what state of the
code gets built.

Change-Id: I8b00d7d79a26ad4aaae529cb496e125398169b50
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Lev Stipakov <lstipakov@gmail.com>
Message-Id: <20230922103936.37230-1-frank@lichtenheld.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg27060.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 37d6c61a3decf64d0db1cd3d033483c9db5c4c91)