Generate Scylla service monitors automatically (#3983)

## Motivation

There's an option that we can use in our values files that will create service monitors identical to the ones we're creating manually

## Proposal

Create service monitors automatically instead

## Test Plan

Will deploy using this to make sure everything is ok

## Release Plan

- Nothing to do / These changes follow the usual release cycle.

Author: ndr-ds

kubernetes/linera-validator/helmfile.yaml

@@ -13,8 +13,17 @@ helmDefaults:
   recreatePods: false
   kubeContext: {{ .Values.kubeContext | quote }}
 
-{{- if or .Values.usingLocalSsd .Values.usingRecommendedScyllaDbSettings }}
 hooks:
+  - events: ["prepare"]
+    showlogs: true
+    command: bash
+    args:
+      - -lc
+      - |
+        set -euxo pipefail
+        echo "Installing Prometheus ServiceMonitor CRD…"
+        kubectl apply -f https://raw.githubusercontent.com/prometheus-operator/prometheus-operator/main/example/prometheus-operator-crd/monitoring.coreos.com_servicemonitors.yaml
+{{- if or .Values.usingLocalSsd .Values.usingRecommendedScyllaDbSettings }}
   - events: ["prepare"]
     showlogs: true
     command: bash

kubernetes/linera-validator/scylla-manager.values.yaml

@@ -27,3 +27,5 @@ scylla:
       requests:
         cpu: 1
         memory: 2Gi
+serviceMonitor:
+  create: true

kubernetes/linera-validator/scylla.values.yaml.gotmpl

@@ -15,3 +15,5 @@ racks:
       requests:
         cpu: 1
         memory: 2Gi
+serviceMonitor:
+  create: true