use java 17 as default

Author: smuzaffar

lumi/jenkins_java.sh

@@ -2,5 +2,5 @@
 
 JENKINS_JAR=$1
 JAVA_CMD="/etc/alternatives/jre_17/bin/java"
-[ -e /etc/alternatives/jre_17/bin/java ] && JAVA_CMD="/etc/alternatives/jre_17/bin/java"
+[ -e /etc/alternatives/jre_21/bin/java ] && JAVA_CMD="/etc/alternatives/jre_21/bin/java"
 $JAVA_CMD --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/java.lang.reflect=ALL-UNNAMED -jar ${JENKINS_JAR} -jar-cache $(dirname ${JENKINS_JAR})/tmp