Support GitLab Environment Toolkit (GET)

Summary

We'll eventually want GitLab Environment Toolkit (GET) to support deployment using the GitLab Operator in addition to its existing support for the GitLab Charts.

This issue is a placeholder within the Operator issue list for visibility. The upstream issue is available here: gitlab-org/gitlab-environment-toolkit#109 (closed).

Acceptance criteria

• gitlab-org/gitlab-environment-toolkit#109 (closed) is closed
• Follow-up issue(s) for GitLab Operator are created
• Follow-up issue(s) for Gitlab Operator are addressed