GitLab managed apps readiness for Kubernetes 1.16

Problem to solve

Kubernetes 1.16 no longer will be serving extensions/* and apps/beta* API versions, all resources should stop using them.

GitLab-managed apps should continue to be installable and usable for Kubernetes 1.16 and up

Proposal

Ensure that the chart versions used by GitLab managed apps use Kubernetes 1.16 compatible resources

Further details

The upstream charts themselves may not be ready.

Chart	Notes	Status
helm	Awaiting https://github.com/helm/helm/pull/6462	!19054 (closed) !18924 (merged) ✅
nginx-ingress	Fixed as of https://github.com/helm/charts/commit/2f322ebbaaa9ac984daa5939c1296c507b3ba1e0 (v1.22.0)	!18047 (merged) ✅
jetstack/cert-manager	Compatible, see https://cert-manager.readthedocs.io/en/latest/tasks/upgrading/upgrading-0.8-0.9.html	✅
jupyterhub	v1.16 compatible since https://github.com/jupyterhub/zero-to-jupyterhub-k8s/commit/05b4e8cc9bb6bf96cf8bbc7848dad5793d6704c6 (0.8.2)	✅
runner	v1.16 compatible since gitlab-org/charts/gitlab-runner!167 (merged)	!18879 (merged) ✅
prometheus	Need to pull in https://github.com/helm/charts/pull/17268	#38304 (closed)
knative	Fixed as of https://github.com/triggermesh/charts/commit/e37a3265bab3c1aa61d6122ec52a221c9ace2138.	!21361 (merged)

Relevant links

• https://kubernetes.io/blog/2019/07/18/api-deprecations-in-1-16/
• https://kubernetes.io/blog/2019/09/18/kubernetes-1-16-release-announcement/