Use CNG images for KAS

What does this MR do?

Switches the GitLab KAS image repository to CNG.

Related issues

gitlab-org/cluster-integration/gitlab-agent#224 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened

Test plan

Installed the chart on this branch with KAS enabled and verified that KAS runs:

# create a local cluster
kind create cluster --config examples/kind/kind-no-ssl.yaml
# install the chart with KAS enabled
helm upgrade --install gitlab . -f examples/kind/values-base.yaml -f examples/kind/values-no-ssl.yaml --set global.kas.enabled=true
# grab the logs
kubectl logs deployment/gitlab-kas

Log output

Found 2 pods, using pod/gitlab-kas-654d4fd74b-mxpr2
{"level":"info","time":"2022-02-18T17:11:45.580Z","msg":"Private API endpoint is up","net_network":"tcp","net_address":"[::]:8155"}
{"level":"info","time":"2022-02-18T17:11:45.580Z","msg":"API endpoint is up","net_network":"tcp","net_address":"[::]:8153"}
{"level":"info","time":"2022-02-18T17:11:45.580Z","msg":"Kubernetes API endpoint is up","mod_name":"kubernetes_api","net_network":"tcp","net_address":"[::]:8154"}
{"level":"info","time":"2022-02-18T17:11:45.580Z","msg":"Observability endpoint is up","mod_name":"observability","net_network":"tcp","net_address":"[::]:8151"}
{"level":"info","time":"2022-02-18T17:11:45.581Z","msg":"Agentk API endpoint is up","net_network":"tcp","net_address":"[::]:8150","is_websocket":true}