Fix clusterchecks leader election (#10468)

* Add service name envvar to the DCA

Signed-off-by: Xavier Vello <xavier.vello@datadoghq.com>

* Reword cluster-agent token note to account for token not synced issues

Signed-off-by: Xavier Vello <xavier.vello@datadoghq.com>

* update version

Signed-off-by: Xavier Vello <xavier.vello@datadoghq.com>

stable/datadog/Chart.yaml

@@ -1,5 +1,5 @@
 name: datadog
-version: 1.15.0
+version: 1.15.1
 appVersion: 6.6.0
 description: DataDog Agent
 keywords:

stable/datadog/templates/NOTES.txt

@@ -53,6 +53,9 @@ Create an application key at https://app.datadoghq.com/account/settings#api
 Because you enabled the Cluster Agent but did not provide a token, a random token was generated.
 This token is used to secure the communication between the Agents and the Cluster Agent.
 
+Make sure to recreate all pods on upgrade (with the --recreate-pods flag) to ensure all
+agents use the same shared token.
+
   {{- end }}
 
 {{- end }}

stable/datadog/templates/cluster-agent-deployment.yaml

@@ -74,6 +74,8 @@ spec:
           {{- if .Values.datadog.collectEvents }}
           - name: DD_COLLECT_KUBERNETES_EVENTS
             value: {{ .Values.datadog.collectEvents | quote}}
+          - name: DD_CLUSTER_AGENT_KUBERNETES_SERVICE_NAME
+            value: {{ template "datadog.clusterAgent.fullname" . }}
           {{- end }}
           - name: DD_CLUSTER_AGENT_AUTH_TOKEN
             valueFrom: