Add a way to install Helm and add a job to build Review App related images
What does this MR do and why?
This adds a way to install Helm and adds a job for the Review App related images, as it was missing from !432 (comment 668596197).
The image will be available as registry.gitlab.com/gitlab-org/gitlab-build-images/ruby-3.0:gcloud-383-kubectl-1.23-helm-3.5
: https://gitlab.com/gitlab-org/gitlab-build-images/-/jobs/2662505381
Edited by Rémy Coutable