Now that packets flow for VIPServices, the last piece needed to start
serving them from a ProxyGroup is config to tell the proxy Pods which
services they should advertise.
Updates tailscale/corp#24795
Change-Id: Ic7bbeac8e93c9503558107bc5f6123be02a84c77
Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>