Make sure Ubuntu is using JDK21 when connecting to Main node

[peterzhuamazon]

Description

Make sure Ubuntu is using JDK21 when connecting to Main node

Issues Resolved

opensearch-project/opensearch-build#4771
#484

Jul 23, 2024 12:04:05 AM hudson.plugins.ec2.EC2Cloud
INFO: Creating ~/.hudson-run-init
Jul 23, 2024 12:04:05 AM hudson.plugins.ec2.EC2Cloud
INFO: Verifying: java -fullversion
openjdk full version "11.0.22+7"
Jul 23, 2024 12:04:08 AM hudson.plugins.ec2.EC2Cloud
INFO: Verifying: which scp
/usr/bin/scp
Jul 23, 2024 12:04:08 AM hudson.plugins.ec2.EC2Cloud
INFO: Copying remoting.jar to: /tmp
Jul 23, 2024 12:04:08 AM hudson.plugins.ec2.EC2Cloud
INFO: Launching remoting agent (via Trilead SSH2 Connection):  java  -jar /tmp/remoting.jar -workDir /var/jenkins
<===[JENKINS REMOTING CAPACITY]===>Remoting version: 3160.vd76b_9ddd10cc
Launcher: EC2UnixLauncher
Communication Protocol: Standard in/out
This is a Unix agent
Evacuated stdout
Agent successfully connected and online

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