fix(kube-stack): extend MetricRelabeling schema (#2071)

* fix(kube-stack): extend MetricRelabeling schema to support full Prometheus relabel_config

The MetricRelabeling schema was too restrictive, only allowing action, regex,
and sourceLabels properties. This prevented using standard Prometheus
relabel_config features like targetLabel and replacement for label
transformation use cases.

Changes:
- Add missing fields to MetricRelabeling: targetLabel, replacement, separator, modulus
- Remove incorrect required constraint (different actions need different fields)
- Align KubeServiceMonitor relabeling fields to use MetricRelabeling schema
- Align Monitor.relabelings to use MetricRelabeling schema for consistency

This enables use cases like:
  metricRelabelings:
    - sourceLabels: [namespace]
      targetLabel: k8s.namespace.name
      action: replace

Affected components now properly support full relabel_config:
- kube-state-metrics.prometheus.monitor.metricRelabelings
- kubeApiServer.serviceMonitor.metricRelabelings
- prometheus-node-exporter.prometheus.monitor.metricRelabelings
- All KubeServiceMonitor relabeling fields
- All Monitor relabeling fields

* chore(kube-stack): bump chart version to 0.13.2

---------

Co-authored-by: Tyler Helmuth <12352919+TylerHelmuth@users.noreply.github.com>

Author: szibis

charts/opentelemetry-kube-stack/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v2
 name: opentelemetry-kube-stack
-version: 0.14.0
+version: 0.14.1
 description: |
   OpenTelemetry Quickstart chart for Kubernetes.
   Installs an operator and collector for an easy way to get started with Kubernetes observability.

charts/opentelemetry-kube-stack/values.schema.json

@@ -3819,11 +3819,15 @@
         },
         "metricRelabelings": {
           "type": "array",
-          "items": {}
+          "items": {
+            "$ref": "#/$defs/MetricRelabeling"
+          }
         },
         "relabelings": {
           "type": "array",
-          "items": {}
+          "items": {
+            "$ref": "#/$defs/MetricRelabeling"
+          }
         },
         "additionalLabels": {
           "$ref": "#/$defs/AdditionalLabels"
@@ -3860,11 +3864,15 @@
         },
         "dnsmasqMetricRelabelings": {
           "type": "array",
-          "items": {}
+          "items": {
+            "$ref": "#/$defs/MetricRelabeling"
+          }
         },
         "dnsmasqRelabelings": {
           "type": "array",
-          "items": {}
+          "items": {
+            "$ref": "#/$defs/MetricRelabeling"
+          }
         },
         "scheme": {
           "type": "string"
@@ -3982,7 +3990,9 @@
         },
         "relabelings": {
           "type": "array",
-          "items": {}
+          "items": {
+            "$ref": "#/$defs/MetricRelabeling"
+          }
         },
         "jobLabel": {
           "type": "string"
@@ -4022,13 +4032,20 @@
           "items": {
             "type": "string"
           }
+        },
+        "targetLabel": {
+          "type": "string"
+        },
+        "replacement": {
+          "type": "string"
+        },
+        "separator": {
+          "type": "string"
+        },
+        "modulus": {
+          "type": "integer"
         }
       },
-      "required": [
-        "action",
-        "regex",
-        "sourceLabels"
-      ],
       "title": "MetricRelabeling"
     },
     "Selector": {