Move non-ECS fields from root level event #897

Motivation

Currently, having custom (non ECS) fields at the root level of vulnerability is a wrong doing
It can cause conflicts with other integrations

The proposed way for integrations having customized fields is to add them under the package name
In our case, cloud_security_posture.*

Definition of done

• Move/remove root level fields like: type, class, cluster_id and make sure cloudbeat's events follow the specified guideline
• Fields that already exist prior 8.8, for backward compatibility, add to the ingest pipeline rules to remove these fields / move them to the proper place (only if they are not being used in kibana)
• Create follow-up for custom fields we want to be part of ECS
• Explore if there are more fields that weren't mentioned in DOD

Out of scope

Related tasks/epics