Use Helm to deploy Redis cluster

[esune]

Our Redis cluster is currently deployed using an internally developed/maintained deployment template. In order to reduce the effort required to maintain the deployment, we should switch to using a community-supported deployment descriptor such as https://github.com/bitnami/charts/tree/main/bitnami/redis-cluster . This would also likely help us with the issues we are having with defunct PID processes - see bitnami/charts#5328

Contextually, we should look into adding Redis to the resources managed by ArgoCD - it should be simpler when using Helm.