drop: Remove K8up as unused backup operator

This patch drops K8up as operator/controller from all clusters. Since
it's not really used there is no point in keeping it around.

infrastructure/k8up/README.md

-K8up
-===
-
-This component provides backup capabilities to the cluster. The backup repository and objects are namespaced, providing good isolation for all backups.
-
-
-Nice to knows
----
-
-- This operator requires separate installation of CRD. This was not part of this module, which made it essentially broken. It's fixed now.
-
-Links
----
-
-- [Docs](https://k8up.io)
-- [Helm Chart](https://artifacthub.io/packages/helm/appuio/k8up)
-- [Source Code](https://github.com/k8up-io/k8up)
-- [Forum](https://github.com/k8up-io/k8up/discussions)

infrastructure/k8up/kustomization.yaml

-apiVersion: kustomize.config.k8s.io/v1beta1
-kind: Kustomization
-namespace: k8up-system
-resources:
-  - namespace.yaml
-  - repository.yaml
-  - k8up-crd.yaml
-  - release.yaml
-  - ../../shared/networkpolicies/allow-from-same-namespace.yaml
-  - ../../shared/networkpolicies/allow-from-monitoring.yaml
-patchesStrategicMerge:
-  - networkpolicy.yaml

infrastructure/k8up/namespace.yaml

-apiVersion: v1
-kind: Namespace
-metadata:
-  name: k8up-system
-  labels:
-    pod-security.kubernetes.io/audit: restricted
-    pod-security.kubernetes.io/enforce: baseline
-    pod-security.kubernetes.io/warn: restricted
-    pod-security.kubernetes.io/audit-version: v1.26
-    pod-security.kubernetes.io/enforce-version: v1.23
-    pod-security.kubernetes.io/warn-version: v1.26
-    kyverno.shivering-isles.com/class: "system"

infrastructure/k8up/networkpolicy.yaml

----
-apiVersion: networking.k8s.io/v1
-kind: NetworkPolicy
-metadata:
-  name: allow-from-monitoring
-spec:
-  podSelector:
-    matchLabels:
-      app.kubernetes.io/instance: k8up
-      app.kubernetes.io/name: k8up

infrastructure/k8up/release.yaml

-apiVersion: helm.toolkit.fluxcd.io/v2beta1
-kind: HelmRelease
-metadata:
-  name: k8up
-  namespace: k8up-system
-spec:
-  releaseName: k8up
-  chart:
-    spec:
-      chart: k8up
-      sourceRef:
-        kind: HelmRepository
-        name: k8up
-        namespace: k8up-system
-      version: 2.0.5
-  interval: 5m
-  values:
-    metrics:
-      serviceMonitor:
-        enabled: true
-      prometheusRule:
-        enabled: true

infrastructure/k8up/repository.yaml

-apiVersion: source.toolkit.fluxcd.io/v1beta1
-kind: HelmRepository
-metadata:
-  name: k8up
-  namespace: k8up-system
-spec:
-  interval: 30m
-  url: https://charts.appuio.ch

infrastructure/kustomization.yaml

@@ -12,7 +12,6 @@ resources:
   - longhorn
   - monitoring
   - flux-system
-  - k8up
   - postgres
   - redis
   - kubenav