Meta-task tracking things needed for helm 3 migration
[x] import and build helm3
[x] ensure compatibility of helm plugins
[x] [[ https://gerrit.wikimedia.org/g/operations/debs/helm-diff | helm-diff ]] supports helm3
[ ] ~~[[ https://gerrit.wikimedia.org/g/operations/debs/helm-secrets | helm-secrets ]] seems to be compatible to helm 3 (https://github.com/zendesk/helm-secrets/issues/145). ~~ (we're not using this anywhere)
[x] [[ https://gerrit.wikimedia.org/r/admin/projects/operations/debs/helmfile | helmfile ]] is not a plugin, looks like it supports helm3
[x] add helm3 stuff to puppet
[] figure a way to gradually migrate helmfile.d/services (this should only be done after k8s has been upgraded to >= 1.16 in all clusters)
* https://helm.sh/docs/topics/v2_v3_migration/
* https://helm.sh/blog/migrate-from-helm-v2-to-helm-v3/
[] alternatively migrate all services at once (on a depooled cluster), verify success and do so on the second one
[x] We need an alternative to recreate pods
[] We might need additional annotations to helm tests (see comments)