Remove automatic service

Remove automatic service

This has been replaced by openvpnserv2 since 2.4.0 and we have
stopped setting up this service in the installer since 2.5.0.

Get rid of the unused code. The mechanics of supporting multiple
services with the same executable is retained for possible future use.

For backwards compatibility, the command line option -instance
is unchanged as "-instance <name> id" although <name>="interactive"
is the only supported value now.

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Lev Stipakov <lstipakov@gmail.com>
Message-Id: <1616991798-7179-1-git-send-email-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg21890.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>