Improve HelmClient and KubernetesClient

What does this MR do?

Port of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7772 to CE.

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• [-] Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides