Make sure that the Scylla config ConfigMap exists when Scylla gets created (#4871)

## Motivation

We're setting Scylla settings using this ConfigMap, but there's actually
no guarantee that it will exist by the time Scylla starts. I've seen
networks deployed that just ignore the ConfigMap and use default
settings, for example, because the ConfigMap wasn't created yet when
Scylla started.

## Proposal

Enforce that the ConfigMap will be created before Scylla starts.

## Test Plan

Deployed a network, it uses the ConfigMap options more reliably now

## Release Plan

- These changes should be backported to the latest `testnet` branch,
then
    - be released in a validator hotfix.

Author: ndr-ds

kubernetes/linera-validator/helmfile.yaml

@@ -97,8 +97,30 @@ releases:
       - scylla-operator/scylla-operator
     values:
       - {{ env "LINERA_HELMFILE_VALUES_SCYLLA" | default "scylla.values.yaml.gotmpl" }}
-    {{- if and .Values.gcpRun .Values.usingLocalSsd }}
     hooks:
+      - events: ["presync"]
+        showlogs: true
+        command: bash
+        args:
+          - -c
+          - |
+            set -euxo pipefail
+
+            kube_args=(
+              {{- if .Values.kubeContext }}
+              --context {{ .Values.kubeContext }}
+              {{- end }}
+              {{- if .Values.kubeConfigPath }}
+              --kubeconfig {{ .Values.kubeConfigPath }}
+              {{- end }}
+            )
+
+            echo "Ensuring scylla namespace exists..."
+            kubectl "${kube_args[@]}" create namespace scylla 2>/dev/null || true
+
+            echo "Ensuring scylla-config ConfigMap exists before deploying ScyllaCluster..."
+            kubectl "${kube_args[@]}" apply -f templates/scylla-config.yaml
+    {{- if and .Values.gcpRun .Values.usingLocalSsd }}
       - events: ["presync"]
         showlogs: true
         command: bash

kubernetes/linera-validator/templates/scylla-config.yaml

@@ -3,6 +3,11 @@ kind: ConfigMap
 metadata:
   name: scylla-config
   namespace: scylla
+  labels:
+    app.kubernetes.io/managed-by: Helm
+  annotations:
+    meta.helm.sh/release-name: linera-core
+    meta.helm.sh/release-namespace: default
 data:
   scylla.yaml: |
     query_tombstone_page_limit: 200000