Following the Helm repo deprecation - mitigate impact, and migrate to new charts
Given the deprecation timeline for the central helm repo, we should be using the distributed charts.
https://github.com/helm/charts#deprecation-timeline
> 2020-11-13: the helm stable repo at https://kubernetes-charts.storage.googleapis.com will be deleted
### Definition of done
- [x] Mitigate impact of the stable repo at https://kubernetes-charts.storage.googleapis.com/ disappearing
- https://gitlab.com/gitlab-org/gitlab/-/merge_requests/44875
- https://gitlab.com/gitlab-org/gitlab/-/merge_requests/45472
- https://gitlab.com/gitlab-org/gitlab/-/merge_requests/45487
- https://gitlab.com/gitlab-org/cluster-integration/auto-deploy-image/-/merge_requests/127
- [x] Write blog post about upcoming helm stable removal - https://gitlab.com/gitlab-com/www-gitlab-com/-/merge_requests/66364
- [x] Open individual issues to migrate to new location
- [ ] Migrate each app to use new canonical chart
| chart | Mitigation | Deprecated chart | New chart | Notes|
| ------ | ----------| ------ | ------ | ------ |
| PostgreSQL | Mitigated in 13.6. Will be backported | https://github.com/helm/charts/tree/master/stable/postgresql#this-helm-chart-is-deprecated | https://github.com/bitnami/charts/tree/master/bitnami/postgresql | gitlab~2976578 Split off to https://gitlab.com/gitlab-org/gitlab/-/issues/263778 |
| Nginx Ingress | Mitigated in 13.5, backported to 13.3. Will be backported to 13.4 | https://github.com/helm/charts/tree/master/stable/nginx-ingress | https://github.com/kubernetes/ingress-nginx | Based on https://github.com/helm/charts/pull/22823, see also https://github.com/kubernetes/ingress-nginx/issues/5161 gitlab~2953641 |
| prometheus | Mitigated in 13.5, backported to 13.3. Will be backported to 13.4 | https://github.com/helm/charts/tree/master/stable/prometheus | https://github.com/prometheus-community/helm-charts | No response to https://groups.google.com/g/prometheus-users/c/oHU4bktoqKs gitlab~3103458 |
| fluentd | Mitigated in 13.5, backported to 13.3. Will be backported to 13.4 | https://github.com/helm/charts/tree/master/stable/fluentd | https://github.com/fluent/helm-charts or https://github.com/bitnami/charts/tree/master/bitnami/fluentd | See https://github.com/helm/charts/issues/21235 gitlab~3103458 |
| sentry | Mitigated in 13.6, no backports planned | https://github.com/helm/charts/tree/master/stable/sentry | https://github.com/sentry-kubernetes/charts ? | gitlab~3103458 |
epic