poststartup script moved to extra container, non init

elasticsearch/values.yaml

@@ -174,13 +174,12 @@ extraVolumeMounts:
 
 extraContainers: 
   - name: elasticsearch-template-loader
-    image: alpine:3.20
+    image: docker.io/library/elasticsearch:8.5.1
     command:
         - /bin/bash
         - -c
         - |
           set -ex
-          apk add --no-cache bash curl coreutils
           echo "[template-loader] Waiting for Elasticsearch at $ES_URL..."
           for i in $(seq 1 ${MAX_RETRIES:-30}); do
             if curl -s "$ES_URL" >/dev/null; then