Bump to JDK21 for build (#87)

Author: gareth-ellis

cars/v1/vanilla/config.ini

@@ -18,7 +18,7 @@ jdk.unbundled.release_url = https://artifacts.elastic.co/downloads/elasticsearch
 
 docker_image=docker.elastic.co/elasticsearch/elasticsearch
 # major version of the JDK that is used to build Elasticsearch
-build.jdk = 17
+build.jdk = 21
 # list of JDK major versions that are used to run Elasticsearch
-runtime.jdk = 22,21,20,19,18,17,16,15,14,13,12,11
+runtime.jdk = 23,22,21,20,19,18,17,16,15,14,13,12,11
 runtime.jdk.bundled = true