Modify k8s-workloads/gitlab.com to support the use of helmfile

Modify k-ctl such that it can support both.

• Update the image to be used after gitlab-com/gl-infra/k8s-workloads/common!46 (merged)
• Update k-ctl to utilize helmfile for deploys instead of helm
• Update any necessary configurations to shrink the amount of cruft inside of the k-ctl script