[TASK] Prepare 8.9 HC for 8.9 alpha release

[hisImminence]

Motivation

The 8.9 HC is still referencing 8.8 images (e.g. here). To prepare for the 8.9 release, we should start integrating the 8.9 images and make sure the necessary tb discovered changes are in the helm chart.

Actions

• Start a PR with the release candidate or snapshot
  • Debug and consult app teams early for configuration changes not yet documented.