SSL handshake with windows client fails on Elastic Agent after Single Node to Cluster Upgrade

[rishagg01]

Release 2.3.0 - When user completes LME Single Node to Cluster Upgrade, the Windows Client machine with Elastic Agent enrolled goes into Unhealthy state after conversion and SSL handshake fails.

Steps to Reproduce:

1. Set up a 3 node cluster with a windows client machine. Used the documentation for Release 2.3.0:
   https://github.com/cisagov/LME/blob/integrate-develop/testing/v2/installers/cluster_installer/README.md
   Follow the manual steps. Do not run Step 8, cluster install.

2. On the master, install single node LME from the LME main branch from LME Github.

3. On the windows client machine, added elastic agent, wazuh agent and Sysmon.

4. Then switched to integrate-develop branch and created cluster inventory file.

5. Then ran the upgrade to cluster script: ./scripts/convert_to_cluster.sh --skip-inventory. When user is prompted to run back up, I choose No. The script completes succesfully.

6. Login to Kibana portal and navigate to Fleet menu option. The window client shows yellow as displayed in screenshot.

Note: If the window client node shows Green (Healthy) initially, give it 2-5 minutes and it turns Yellow.

[cbaxley]

I was able to fix this by keeping the ca and regenerating only the leaf nodes. It should work now.