Add warning of potential data loss on Elastic Stack upgrade

Description

When a user on Elastic Stack chart versions 1.9.0 or 2.0.0 upgrades their cluster to 3.0.0, there is a potential of them loosing access to old logs data.

More specifically, any logs where the physical host has since terminated, or where the log file has been removed from disk will not get re-indexed after the upgrade.

We should add a popup when they click on the upgrade button to confirm the action.

Warning text

Warning: potential data loss

Your Elasticsearch cluster will be re-created during this upgrade. Your logs will be re-indexed, and you will lose historical logs from hosts terminated in the last 30 days.

More context !30528 (comment 337478383)