Stop registering Kube cluster named after Teleport cluster

[nklaassen]

Issue #6226

There are essentially 3 ways a Teleport Kubernetes service can be configured inside a Kubernetes cluster, listed below.

This PR only changes the first case where the new style Proxy Service is used (kube_listen_addr set, no kubernetes: subsection) inside of a Kubernetes cluster. Currently, in this case, the Proxy service will publish a Kubernetes cluster with the same name as the Teleport cluster. This is not desired - the Kubernetes cluster name should only be published by the kubernetes_service.

1. New Proxy Service style with Kubernetes Service

auth_service:
  cluster_name: peach

proxy_service:
  kube_listen_addr: 0.0.0.0:3026

kubernetes_service:
  enabled: yes
  listen_addr: 0.0.0.0:3027
  kube_cluster_name: banana

Current behaviour:

$ tsh kube ls
peach
banana

New behaviour:

$ tsh kube ls
banana

2. Legacy Proxy Service style without Kubernetes Service

auth_service:
  cluster_name: peach

proxy_service:
  kubernetes:
    enabled: yes
    listen_addr: 0.0.0.0:3026

Current behaviour (unchanged):

$ tsh kube ls
peach

3. Legacy Proxy Service style with Kubernetes Service

auth_service:
  cluster_name: peach

proxy_service:
  kubernetes:
    enabled: yes
    listen_addr: 0.0.0.0:3026

kubernetes_service:
  enabled: yes
  listen_addr: 0.0.0.0:3027
  kube_cluster_name: banana

Current behaviour (unchanged):

$ tsh kube ls
peach
banana

Backwards Compatability

Anyone currently using the new style Proxy Service with kube_listen_addr set, inside of a Kubernetes cluster, will have the current listed Kubernetes cluster named after the teleport cluster "disappear". This may break automation that relies on that "cluster".

Testing

• configuration_test.go and auth_test.go updated
• manually tested each configuration on a local Kubernetes cluster

[tcsc]

Looks OK to me.

[nklaassen]

Tagging @klizhentas for UX approval

[klizhentas]

@nklaassen LGTM after you update CHANGELOG.md with a breaking change notification similar to others (see examples in changelog) (so we don't forget)

[klizhentas]

LGTM assuming changelog update

[nklaassen]

@nklaassen LGTM after you update CHANGELOG.md with a breaking change notification similar to others (see examples in changelog) (so we don't forget)

Thanks, I started a placeholder 7.0 section in CHANGELOG.md with a Breaking Changes section including this