fix(etcd): remove destructive post-upgrade cert-regeneration hook (#2462)

## What this PR does

Removes the `post-upgrade` Helm hook in `packages/extra/etcd` that was
`kubectl delete`ing the etcd TLS chain (`etcd-ca-tls`,
`etcd-peer-ca-tls`,
`etcd-client-tls`, `etcd-peer-tls`, `etcd-server-tls`) and then deleting
etcd pods on every chart upgrade.

The hook was gated by a semver compare of a stored
`etcd-deployed-version`
ConfigMap against `2.6.1`. That gate was written when chart versions
looked
like `2.6.0`, `2.6.1`, etc. Since commit `f871fbdb` ("Remove
versions_map
logic") all chart versions are stamped as `0.0.0+<git-hash>`, which per
semver is always `< 2.6.1`, so the gate always evaluates to "regenerate
certs" and the destructive hook fires on every upgrade.

On clusters running Kamaji-managed tenant control planes the consequence
is
severe: wiping the etcd CA triggers cert-manager to re-issue it with a
brand-new CA, but Kamaji's `datastore-certificate` Secrets still carry
the
old CA bundle mounted into tenant `kube-apiserver` pods. Those
apiservers
hit `x509: certificate signed by unknown authority` against
`etcd.<ns>.svc:2379` and go into CrashLoopBackOff until each tenant
`DataStore` is individually force-reconciled and the Deployments rolled.

Commit `47d81f70` ("Disabled private key rotation in CA certs") already
fixed the underlying `rotationPolicy: Always` issue the hook was written
to
paper over in March 2025, so the migration has no remaining use.

Changes:
- Delete `templates/hook/{job,role,rolebinding,serviceaccount}.yaml`
- Delete `templates/version.yaml` (only the hook read
`etcd-deployed-version`)
- Add `tests/no-post-upgrade-hook_test.yaml` as a regression guard — if
`templates/hook/job.yaml` or `templates/version.yaml` is ever brought
back,
  `make unit-tests` fails

### Release note

```release-note
fix(etcd): remove destructive post-upgrade cert-regeneration hook. Previously the etcd chart ran a `post-upgrade` hook on every Helm upgrade that deleted etcd TLS Secrets and pods, causing cert-manager to re-issue the etcd CA. On clusters with Kamaji-managed tenant control planes this put every tenant `kube-apiserver` into CrashLoopBackOff until each DataStore was manually re-reconciled. The hook was a one-shot `2.6.0 -> 2.6.1` migration that became a permanent footgun once chart versioning moved to `0.0.0+<git-hash>` and the underlying `rotationPolicy: Always` issue was fixed in commit `47d81f70`. This is behavior removal, not cosmetic cleanup.
```


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Tests**
* Added Helm chart test suite verifying absence of post-upgrade hook Job
and version ConfigMap.

* **Chores**
* Removed post-upgrade hook Job and associated RBAC resources (Role,
RoleBinding, ServiceAccount).
  * Removed version ConfigMap.
  * Added `test` target to Makefile for running Helm chart unit tests.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/extra/etcd/Makefile

@@ -5,3 +5,6 @@ include ../../../hack/package.mk
 generate:
 	cozyvalues-gen -v values.yaml -s values.schema.json -r README.md
 	../../../hack/update-crd.sh
+
+test:
+	helm unittest .

packages/extra/etcd/templates/hook/job.yaml

@@ -1,39 +0,0 @@
-{{- $shouldUpdateCerts := true }}
-{{- $configMap := lookup "v1" "ConfigMap" .Release.Namespace "etcd-deployed-version" }}
-{{- if $configMap }}
-  {{- $deployedVersion := index $configMap "data" "version" }}
-  {{- if $deployedVersion | semverCompare ">= 2.6.1" }}
-    {{- $shouldUpdateCerts = false }}
-  {{- end }}
-{{- end }}
-
-{{- if $shouldUpdateCerts }}
----
-apiVersion: batch/v1
-kind: Job
-metadata:
-  name: etcd-hook
-  annotations:
-    helm.sh/hook: post-upgrade
-    helm.sh/hook-delete-policy: before-hook-creation,hook-succeeded
-spec:
-  template:
-    metadata:
-      labels:
-        policy.cozystack.io/allow-to-apiserver: "true"
-    spec:
-      serviceAccountName: etcd-hook
-      containers:
-        - name: kubectl
-          image: docker.io/alpine/k8s:1.33.4
-          command:
-          - sh
-          args:
-            - -exc
-            - |-
-              kubectl --namespace={{ .Release.Namespace }} delete secrets etcd-ca-tls etcd-peer-ca-tls 
-              sleep 10
-              kubectl --namespace={{ .Release.Namespace }} delete secrets etcd-client-tls etcd-peer-tls etcd-server-tls
-              kubectl --namespace={{ .Release.Namespace }} delete pods --selector=app.kubernetes.io/instance=etcd,app.kubernetes.io/managed-by=etcd-operator,app.kubernetes.io/name=etcd,cozystack.io/service=etcd
-      restartPolicy: Never
-{{- end }}

packages/extra/etcd/templates/hook/role.yaml

@@ -1,26 +0,0 @@
-apiVersion: rbac.authorization.k8s.io/v1
-kind: Role
-metadata:
-  annotations:
-    helm.sh/hook: post-upgrade
-    helm.sh/hook-delete-policy: before-hook-creation,hook-succeeded
-  name: etcd-hook
-rules:
-- apiGroups:
-  - ""
-  resources:
-  - secrets
-  - pods
-  verbs:
-  - get
-  - list
-  - watch
-  - delete
-- apiGroups:
-  - ""
-  resources:
-  - configmaps
-  verbs:
-  - get
-  - list
-  - watch

packages/extra/etcd/templates/hook/rolebinding.yaml

@@ -1,15 +0,0 @@
-apiVersion: rbac.authorization.k8s.io/v1
-kind: RoleBinding
-metadata:
-  name: etcd-hook
-  annotations:
-    helm.sh/hook: post-upgrade
-    helm.sh/hook-delete-policy: before-hook-creation,hook-succeeded
-roleRef:
-  apiGroup: rbac.authorization.k8s.io
-  kind: Role
-  name: etcd-hook
-subjects:
-  - kind: ServiceAccount
-    name: etcd-hook
-    namespace: {{ .Release.Namespace | quote }}

packages/extra/etcd/templates/hook/serviceaccount.yaml

@@ -1,7 +0,0 @@
-apiVersion: v1
-kind: ServiceAccount
-metadata:
-  name: etcd-hook
-  annotations:
-    helm.sh/hook: post-upgrade
-    helm.sh/hook-delete-policy: before-hook-creation,hook-succeeded

packages/extra/etcd/templates/version.yaml

@@ -1,6 +0,0 @@
-apiVersion: v1
-kind: ConfigMap
-metadata:
-  name: etcd-deployed-version
-data:
-  version: {{ .Chart.Version }}

packages/extra/etcd/tests/no-post-upgrade-hook_test.yaml

@@ -0,0 +1,34 @@
+suite: etcd chart does not ship a destructive post-upgrade cert-regeneration hook
+
+release:
+  name: etcd
+  namespace: tenant-root
+
+templates:
+  - templates/check-release-name.yaml
+  - templates/dashboard-resourcemap.yaml
+  - templates/datastore.yaml
+  - templates/etcd-defrag.yaml
+  - templates/hook/job.yaml
+  - templates/podscrape.yaml
+  - templates/prometheus-rules.yaml
+  - templates/version.yaml
+
+tests:
+  - it: renders no Job named etcd-hook
+    documentSelector:
+      path: metadata.name
+      value: etcd-hook
+      skipEmptyTemplates: true
+    asserts:
+      - hasDocuments:
+          count: 0
+
+  - it: renders no ConfigMap named etcd-deployed-version
+    documentSelector:
+      path: metadata.name
+      value: etcd-deployed-version
+      skipEmptyTemplates: true
+    asserts:
+      - hasDocuments:
+          count: 0