openvpn: T2146: delete old client configs
openvpn: T2146: delete old client configs

Previously old client configs for clients that were deleted from
the server stayed in the ccd directory, causing them to still be
used. As we can't know which clients were deleted, this deletes
all the client configs as they are recreated shortly later.

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x