Fix prom config when istio enabled

[ciiiii]

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Motivation

kubernetes-nodes and kubernetes-cadvisor scrape job will be disabled when istio enabled, we should remove the limitation

Modifications

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This change is a trivial rework / code cleanup without any test coverage.

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• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

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[yuweisung]

look clear to me.