* cmd/containerboot,cmd/k8s-operator/deploy/manifests: optionally forward cluster traffic via ingress proxy.
If a tailscale Ingress has tailscale.com/experimental-forward-cluster-traffic-via-ingress annotation, configure the associated ingress proxy to have its tailscale serve proxy to listen on Pod's IP address. This ensures that cluster traffic too can be forwarded via this proxy to the ingress backend(s).
In containerboot, if EXPERIMENTAL_PROXY_CLUSTER_TRAFFIC_VIA_INGRESS is set to true
and the node is Kubernetes operator ingress proxy configured via Ingress,
make sure that traffic from within the cluster can be proxied to the ingress target.
Updates tailscale/tailscale#10499
Signed-off-by: Irbe Krumina <irbe@tailscale.com>