feat(observability): ✨ add VMServiceScrapes + migrate VLogs → VLSingle

- Migrate VLogs CRD to VLSingle (operator.victoriametrics.com/v1beta1)
- Add VMServiceScrape for Forgejo (gitea ns, port http, /metrics)
- Add VMServiceScrape for ArgoCD (argocd ns, port http-metrics)
- Add VMServiceScrape for GARM (garm ns, port metrics)
- Add VMServiceScrape for CoreDNS (kube-system ns, k8s-app: kube-dns)

Ref: IPCEICIS-4618, IPCEICIS-5066

otc/dev.t09.de/stacks/observability/victoria-k8s-stack/manifests/garm-scrape.yaml

@@ -0,0 +1,14 @@
+apiVersion: operator.victoriametrics.com/v1beta1
+kind: VMServiceScrape
+metadata:
+  name: garm
+  namespace: observability
+spec:
+  namespaceSelector:
+    matchNames:
+      - garm
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: garm
+  endpoints:
+    - port: metrics