Update to v9.0.0

List of changes impacting docker-elk:

- [kibana]: Several features now require an encryption key for saved
  objects. Such key must be set via the configuration option
  `xpack.encryptedSavedObjects.encryptionKey`.

  Ref: https://www.elastic.co/guide/en/kibana/8.18/xpack-security-secure-saved-objects.html

- [enterprise-search]: Discontinued in 9.x versions.

  Refs:
  - https://www.elastic.co/guide/en/enterprise-search/8.18/upgrading-to-9-x.html
  - https://www.elastic.co/blog/app-search-to-elasticsearch

.github/workflows/scripts/run-tests-enterprise-search.sh

@@ -1,53 +0,0 @@
-#!/usr/bin/env bash
-
-set -eu
-set -o pipefail
-
-
-source "${BASH_SOURCE[0]%/*}"/lib/testing.sh
-
-
-cid_es="$(container_id elasticsearch)"
-cid_en="$(container_id enterprise-search)"
-
-ip_es="$(service_ip elasticsearch)"
-ip_en="$(service_ip enterprise-search)"
-
-grouplog 'Wait for readiness of Elasticsearch'
-poll_ready "$cid_es" 'http://elasticsearch:9200/' --resolve "elasticsearch:9200:${ip_es}" -u 'elastic:testpasswd'
-endgroup
-
-grouplog 'Wait for readiness of Enterprise Search'
-poll_ready "$cid_en" 'http://enterprise-search:3002/api/ent/v1/internal/health' --resolve "enterprise-search:3002:${ip_en}" -u 'elastic:testpasswd'
-endgroup
-
-log 'Ensuring that App Search API keys were created in Elasticsearch'
-
-query=$( (IFS= read -r -d '' data || echo "$data" | jq -c) <<EOD
-{
-  "query": {
-    "terms": {
-      "name": [ "search-key", "private-key" ]
-    }
-  }
-}
-EOD
-)
-
-declare -a search_args=( '-s' '-u' 'elastic:testpasswd'
-	'http://elasticsearch:9200/.ent-search-actastic-app_search_api_tokens_v3/_search?pretty'
-	'--resolve' "elasticsearch:9200:${ip_es}"
-	'-H' 'Content-Type: application/json'
-	'-d' "${query}"
-)
-
-echo "curl arguments: ${search_args[*]}"
-
-response="$(curl "${search_args[@]}")"
-echo "$response"
-declare -i count
-count="$(jq -rn --argjson data "${response}" '$data.hits.total.value')"
-if (( count != 2)); then
-	echo "Expected search and private keys, got ${count} result(s)"
-	exit 1
-fi