Update Kubernetes Helm chart docs

Open Joshua Lambert requested to merge 38828-update-kubernetes-helm-chart-docs into master
  • Clearly state the gitlab chart is deprecated now, so we can free up the name in %10.3 and use it for the cloud native chart.
  • Adjust the timing of the cloud native chart to EOY.
  • Remove gitlab-omnibus going GA.

Closes #38828

Edited by Joshua Lambert