[FEATURE] Add flag '--no-default-agents' on `kagent install` for a minimal kagent installation

[antweiss]

📋 Prerequisites

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📝 Feature Summary

Add flag '--no-default-agents' on kagent install for a minimal kagent installation. This should set all default agents to enabled=false.

❓ Problem Statement / Motivation

• Current default kagent installation creates 10 agents. This makes it too big for training environments (that;s how I stumbled upon this). Moreover - istio, cilium and promql agents are installed without checking if the tools are available in cluster (i.e istio, cilium, prometheus). And in general - I think having a way of creating a minimal installation without editing the values file for the chart would be a great convenience and help with adoption.

💡 Proposed Solution

Add flag '--no-default-agents' on kagent install
Under the hood that would go over the list of agents in the values file and set them to enabled=false
Maybe we should exclude only the k8s-agent...

🔄 Alternatives Considered

• Installing with helm and passing mulitple --set flags
• Installing with helm and providing a custom override values file.

Both ways work but are cumbersome if one just wnats to have a clean install of kagent.

🎯 Affected Service(s)

None

📚 Additional Context

No response

🙋 Are you willing to contribute?

• I am willing to submit a PR for this feature