[BUG] K8s dashboard doesn't support network event export

### Documentation links

Update https://www.elastic.co/guide/en/security/current/kubernetes-dashboard.html (ESS and serverless) to remove the support matrix check marks for network event export (second row in the table).



### Description

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### Which documentation set(s) does this bug apply to?

ESS and serverless

### Release version

_No response_

### Testing environment

-