observability: migrate VictoriaMetrics from helm charts to operator CRDs

The k8s au-syd1 VictoriaMetrics stack ran as two helm charts
(victoria-metrics-cluster + victoria-metrics-agent) and only scraped
in-cluster targets. The victoria-metrics-operator already runs in
vm-system, so move the stack onto operator-managed CRDs. This lets the
VMAgent consume VMServiceScrape/VMPodScrape (auto-converted from
Prometheus ServiceMonitors) and adds Consul service discovery so the
cluster scrapes the same puppet-prod targets as the puppet vmagent.

Changes:
- Add VMCluster `main`: vmstorage 2 replicas (down from 3, replicationFactor
  2, cephrbd-fast-delete 200Gi, 180d retention), vminsert/vmselect 2 replicas
  + HPA (2-10, 60% cpu).
- Add VMAgent `main`: keeps the kubernetes SD jobs (apiservers/nodes/cadvisor),
  selectAllByDefault for VMServiceScrape/VMPodScrape, and a Consul SD job
  against consul.service.consul (puppet Consul) replicating the puppet vmagent
  relabels (keep tag `metrics`, scheme from `metrics_scheme`, job from
  `metrics_job`). TLS verified against the reflected vault-ca-cert (no
  insecure skip-verify).
- Expose vmselect/vminsert/vmagent via Gateway API (traefik-internal Gateway +
  HTTPRoute, http->https redirect), same hostnames as before.
- Remove the two helm charts, their values files, and vendored charts.

apps/base/observability/gateway.yaml

@@ -0,0 +1,117 @@
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  name: vmselect
+  namespace: observability
+  labels:
+    app.kubernetes.io/name: vmselect
+    app.kubernetes.io/instance: victoria-metrics
+    traefik.io/instance: internal
+  annotations:
+    cert-manager.io/cluster-issuer: vault-issuer
+    cert-manager.io/common-name: vmselect.k8s.syd1.au.unkin.net
+    cert-manager.io/private-key-size: "4096"
+    external-dns.alpha.kubernetes.io/hostname: vmselect.k8s.syd1.au.unkin.net
+    external-dns.alpha.kubernetes.io/target: 198.18.200.4
+spec:
+  gatewayClassName: traefik-internal
+  listeners:
+    - name: http
+      port: 80
+      protocol: HTTP
+      hostname: vmselect.k8s.syd1.au.unkin.net
+      allowedRoutes:
+        namespaces:
+          from: Same
+    - name: https
+      port: 443
+      protocol: HTTPS
+      hostname: vmselect.k8s.syd1.au.unkin.net
+      allowedRoutes:
+        namespaces:
+          from: Same
+      tls:
+        mode: Terminate
+        certificateRefs:
+          - group: ""
+            kind: Secret
+            name: vmselect-tls
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  name: vminsert
+  namespace: observability
+  labels:
+    app.kubernetes.io/name: vminsert
+    app.kubernetes.io/instance: victoria-metrics
+    traefik.io/instance: internal
+  annotations:
+    cert-manager.io/cluster-issuer: vault-issuer
+    cert-manager.io/common-name: vminsert.k8s.syd1.au.unkin.net
+    cert-manager.io/private-key-size: "4096"
+    external-dns.alpha.kubernetes.io/hostname: vminsert.k8s.syd1.au.unkin.net
+    external-dns.alpha.kubernetes.io/target: 198.18.200.4
+spec:
+  gatewayClassName: traefik-internal
+  listeners:
+    - name: http
+      port: 80
+      protocol: HTTP
+      hostname: vminsert.k8s.syd1.au.unkin.net
+      allowedRoutes:
+        namespaces:
+          from: Same
+    - name: https
+      port: 443
+      protocol: HTTPS
+      hostname: vminsert.k8s.syd1.au.unkin.net
+      allowedRoutes:
+        namespaces:
+          from: Same
+      tls:
+        mode: Terminate
+        certificateRefs:
+          - group: ""
+            kind: Secret
+            name: vminsert-tls
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  name: vmagent
+  namespace: observability
+  labels:
+    app.kubernetes.io/name: vmagent
+    app.kubernetes.io/instance: victoria-metrics
+    traefik.io/instance: internal
+  annotations:
+    cert-manager.io/cluster-issuer: vault-issuer
+    cert-manager.io/common-name: vmagent.k8s.syd1.au.unkin.net
+    cert-manager.io/private-key-size: "4096"
+    external-dns.alpha.kubernetes.io/hostname: vmagent.k8s.syd1.au.unkin.net
+    external-dns.alpha.kubernetes.io/target: 198.18.200.4
+spec:
+  gatewayClassName: traefik-internal
+  listeners:
+    - name: http
+      port: 80
+      protocol: HTTP
+      hostname: vmagent.k8s.syd1.au.unkin.net
+      allowedRoutes:
+        namespaces:
+          from: Same
+    - name: https
+      port: 443
+      protocol: HTTPS
+      hostname: vmagent.k8s.syd1.au.unkin.net
+      allowedRoutes:
+        namespaces:
+          from: Same
+      tls:
+        mode: Terminate
+        certificateRefs:
+          - group: ""
+            kind: Secret
+            name: vmagent-tls