Remove 21 from the main runtime config

Signed-off-by: Ian Hoang <ianhoang16@gmail.com>

Author: IanHoang

osbenchmark/resources/provision_configs/main/provision_config_instances/v1/vanilla/config.ini

@@ -18,5 +18,5 @@ docker_image=opensearchproject/opensearch
 # major version of the JDK that is used to build OpenSearch
 build.jdk = 21
 # list of JDK major versions that are used to run OpenSearch
-runtime.jdk = 21,17,16,15,14,13,12,11,8
+runtime.jdk = 17,16,15,14,13,12,11,8
 runtime.jdk.bundled = true