Do not create filebeat container when log topic is not set

[jiangpengcheng]

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Motivation

Even no log topic is specified, it will start a filebeat container, we should avoid that

Modifications

Only create filebeat container when log topic is set and the logTopicAgent == sidecar

Verifying this change

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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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