Cut the self-managed stack over to the in-house Cassandra chart and image

Description

The self-managed stack (deploy/stacks/self-managed) still deploys Cassandra through the old Bitnami-wrapping chart and the bitnami-cassandra image. PR #328 ships the in-house chart (helm-nvcf-cassandra) and the infra/cassandra runtime image. This task repoints the stack at them.

Two files change:

• helmfile.d/01-dependencies.yaml.gotmpl: update the cassandra release's pinned version: to the helm-nvcf-cassandra release that CI publishes for the Bitnami removal. The version is assigned by release automation (registered subproject, tag helm-nvcf-cassandra-v*), not hand-set. The chart reference is unchanged - it already resolves to nvcf/helm-nvcf-cassandra.
• global.yaml.gotmpl cassandra: values - remap from the old chart's schema to the new chart's:
  • Runtime image: bitnami-cassandra becomes the nvcf-cassandra image (infra/cassandra).
  • Drop the value blocks the new chart does not consume: the old chart's separate init image (initialization.image, currently alpine-k8s), its dynamicSeedDiscovery.image, and global.security.allowInsecureImages.
  • Migrations image (nvcf-cassandra-migrations): keep - the new chart runs both the init and migration hooks from it.
  • storageClass: no change. The new chart reads global.defaultStorageClass, which the stack already emits via global.storageClass.
  • Confirm resourcesPreset, replicaCount, nodeSelector, and tolerations map onto the new chart's values.

Definition of Done

• The stack deploys Cassandra from helm-nvcf-cassandra + infra/cassandra; no bitnami-cassandra image or old-chart references remain.
• The emitted cassandra: values match the new chart's schema, with no dead old-chart-only keys.
• The stack installs and upgrades end-to-end on a validation cluster: Cassandra reaches Ready, init and migrations complete.

Resources

• #317 (umbrella), #328 (in-house chart + image), #337 (lifecycle-job rendering)

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Start with deploy/stacks/self-managed/helmfile.d/01-dependencies.yaml.gotmpl and global.yaml.gotmpl, then compare the Cassandra values with the in-house chart and image from PR #328. Update the pinned chart release and remove old-chart-only values while confirming the listed settings map correctly. Validate that the stack installs and upgrades, Cassandra becomes Ready, and init and migration hooks complete.