Add k8s cluster name to helm chart. This will allow separating data from
multiple k8s clusters in same streams.
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## Summary by CodeRabbit
- **New Features**
- Updated installation commands for the OpenObserve collector to specify
the Kubernetes cluster name.
- **Bug Fixes**
- Enhanced specificity of commands related to the OpenObserve collector
installation.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->