The kube-apiserver proxy in the operator would only run in
auth proxy mode but thats not always desirable. There are
situations where the proxy should just be a transparent
proxy and not inject auth headers, so do that using a new
env var APISERVER_PROXY and deprecate the AUTH_PROXY env.
THe new env var has three options `false`, `true` and `noauth`.
Updates #8317
Signed-off-by: Maisem Ali <maisem@tailscale.com>