Undo the Terraform bootstrap claim for ArgoCD

toolshed-gke-infra's 20-bootstrap is superseded and never applied; ArgoCD
on GKE was installed by hand as argocd-admin-prd, as the header originally
said. Reverts c83d535 and corrects the same claim in the argo-cd README.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Fn2kUxyYNY4ApytbLiGWeY

helm-templates/argo-cd/README.md

@@ -9,9 +9,11 @@ so every step here is a manual, imperative command run once.
 
 > **Homelab only.** Every `k8s-admin-prd-ase1` path below lives in the
 > homelab `devops-infra-helm-charts` / `devops-infra-argo-config` repos, not
-> in this GCP copy. On GKE, ArgoCD is installed by Terraform
-> (`toolshed-gke-infra/envs/prod/20-bootstrap/argocd.tf`), and its values
-> live in `helm-overrides/gke-toolshed-prd-usc1/argocd-admin-prd/`.
+> in this GCP copy. On GKE the same steps apply with
+> `helm-overrides/gke-toolshed-prd-usc1/argocd-admin-prd/custom-values.yaml`
+> and `devops-infra-argo-config-gcp`'s
+> `values/incubator-infra-gke-toolshed-prd-usc1-values.yaml`.
+> `toolshed-gke-infra/envs/prod/20-bootstrap` is superseded and not applied.
 
 ## 0. Full uninstall (only if resetting)