[Website]: Scaling settings on K8s should be expanded with some considerations

### Type of issue

None

### What documentation page is affected

https://www.elastic.co/docs/reference/fleet/scaling-on-kubernetes

### What happened?

Guidance in the scaling K8s section:
- The statements / guidance is specific to collecting K8s only.
- For Log harvesting, the memory/cpu limits should be re-evalued
- It doesn't consider any other integraiton installed on the same EA (e.g. no System integration)
- To limit the footprint, one might consider disabling self-monitoring of EA & self-collection of logs

### Additional info

This issue has been created following a user requesting for guidance. See linked issue.