chore: migrate to artifactapi helm virtual repo

- replace all helm repos with artifactapi/virtual/helm
- update projects with accepted repos

argocd/projects/platform.yaml

@@ -8,15 +8,7 @@ spec:
   description: Platform infrastructure and core services
   sourceRepos:
     - https://git.unkin.net/unkin/argocd-apps
-    - https://charts.jetstack.io
-    - https://cloudnative-pg.github.io/charts
-    - https://helm.elastic.co
-    - https://helm.releases.hashicorp.com
-    - https://purelb.github.io/purelb/charts
-    - https://intel.github.io/helm-charts/
-    - https://kubernetes-sigs.github.io/external-dns/
-    - https://releases.rancher.com/server-charts/stable
-    - https://victoriametrics.github.io/helm-charts/
+    - https://artifactapi.k8s.syd1.au.unkin.net/api/v1/virtual/helm
     - oci://gcr.io/k8s-staging-nfd/charts
     - oci://ghcr.io/emberstack/helm-charts
     - oci://ghcr.io/woodpecker-ci/helm/woodpecker