CE and EE KubernetesService

KubernetesService does differ significantly between CE and EE:

• https://gitlab.com/gitlab-org/gitlab-ce/blame/master/lib/gitlab/kubernetes.rb vs https://gitlab.com/gitlab-org/gitlab-ee/blame/master/lib/gitlab/kubernetes.rb
• https://gitlab.com/gitlab-org/gitlab-ce/blame/master/app/models/project_services/kubernetes_service.rb vs https://gitlab.com/gitlab-org/gitlab-ee/blame/master/app/models/project_services/kubernetes_service.rb
• https://gitlab.com/gitlab-org/gitlab-ce/blame/master/spec/models/project_services/kubernetes_service_spec.rb vs https://gitlab.com/gitlab-org/gitlab-ee/blame/master/spec/models/project_services/kubernetes_service_spec.rb

We should align these implementations to help in future CE to EE merges.

cc @nick.thomas @dzaporozhets

mentioned in merge request !1997 (merged)

assigned to @nick.thomas

I'll keep this open until we're sure we don't want any further changes to EE

reopened

mentioned in merge request !2168 (merged)

closed via commit 5468bf7e

closed via merge request !2137 (merged)

mentioned in commit aaf5e6b8

mentioned in commit 061b2714