Meta-task tracking things needed for helm 3 migration
Pre-Migration tasks
[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
[x] ~~[[ 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
[x] ~~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/
[x] alternatively find a way to 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
[x] We might need additional annotations to helm tests (see comments)
[x] Find replacement and new workflow for missing Tiller serviceaccount (new RBAC rules and modifications in helmfiles)
[x] Create and verify plan for migration of `codfw` and `eqiad` (see T251305#7492328)
Migration tasks:
[x] verify migration path on `staging-codfw`
[x] re-deploy and verify `staging`
[x] re-deploy and verify `codfw`
[x] re-deploy and verify `eqiad`
Post migration tasks:
[x] remove tiller and tiller service accounts ([742989](https://gerrit.wikimedia.org/r/c/operations/deployment-charts/+/742989))
[x] uninstall `helm2` from hosts (deploy, releases,contint), make `helm3` default ([753026](https://gerrit.wikimedia.org/r/c/operations/puppet/+/753026))
[x] Cleanup boilderplate code in helmfiles ([737034](https://gerrit.wikimedia.org/r/c/operations/deployment-charts/+/737034))
[x] remove environment state values `helmBinary` ([751067](https://gerrit.wikimedia.org/r/c/operations/puppet/+/751067))
[x] bump charts to v2 api version T295750
[x] remove helm2 from CI and rake files ([746864](https://gerrit.wikimedia.org/r/c/operations/deployment-charts/+/746864), [747147](https://gerrit.wikimedia.org/r/c/integration/config/+/747147), [747487](https://gerrit.wikimedia.org/r/c/operations/deployment-charts/+/747487), [747814](https://gerrit.wikimedia.org/r/c/operations/deployment-charts/+/747814), [748701](https://gerrit.wikimedia.org/r/c/operations/deployment-charts/+/748701))
[] Decide on a default `helm.sh/hook-delete-policy` and add it to charts (https://phabricator.wikimedia.org/T251305#7334407 , T276949)