Use /kustomize/ in /terraform/

[NimJay]

Background

• We hope to eventually delete the all-encompassing /release/kubernetes-manifests.yaml file.
• See the /kustomize/kustomization.yaml file. We want to use this for all Online Boutique deployments going forward.

Change Summary

• Online Boutique's Terraform (./terraform) now uses the Kubernetes resources from /kustomize/base/ (via the /kustomize/kustomization.yaml file).

Additional Notes

• I will need to merge this before merging Add DeployStack integration #1142 (review).

Testing Procedure

• We need to test the instructions inside https://github.com/GoogleCloudPlatform/microservices-demo/tree/main/kustomize#deploy-online-boutique-variations-with-kustomize.
• Note: I have not tested this myself (yet). ⚠️

Related PRs or Issues

• Decouple release/ Manifests into Separate Files #375
• Add kustomize support #536

[minherz]

lgtm`ed it assuming that all kustomize tests were already merged.

[NimJay]

assuming that all kustomize tests were already merged.

Unfortunately, the Terraform-related tests (inside the checks of this pull-request) only test terraform validate.
We will need to test terraform apply manually for now.

[NimJay]

I just test this change (i.e., terraform apply with kubectl apply -k ../kustomize/).
Works!
Merging.