Denote kubectl version in CI

What does this MR do?

Denotes kubectl version in CI jobs review_* (review_eks and review_gke) as we have not taken care about Kubernetes versions for review apps of this repository.

review_eks

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.4", GitCommit:"224be7bdce5a9dd0c2fd0d46b83865648e2fe0ba", GitTreeState:"clean", BuildDate:"2019-12-11T12:47:40Z", GoVersion:"go1.12.12", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"15+", GitVersion:"v1.15.12-eks-31566f", GitCommit:"31566f851673e809d4d667b7235ed87587d37722", GitTreeState:"clean", BuildDate:"2020-10-20T23:25:14Z", GoVersion:"go1.12.17", Compiler:"gc", Platform:"linux/amd64"}

https://gitlab.com/gitlab-org/charts/gitlab/-/jobs/1193789554

review_gke

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.4", GitCommit:"224be7bdce5a9dd0c2fd0d46b83865648e2fe0ba", GitTreeState:"clean", BuildDate:"2019-12-11T12:47:40Z", GoVersion:"go1.12.12", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"17+", GitVersion:"v1.17.17-gke.3000", GitCommit:"4e9d32bd87bb5644183bae27249c6021ddb89436", GitTreeState:"clean", BuildDate:"2021-02-23T09:19:15Z", GoVersion:"go1.13.15b4", Compiler:"gc", Platform:"linux/amd64"}

Related issues

n/a

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened