Add comments to getTestJindoEngineNode in pkg/ddc/jindo/dataset.go

[jzr205220020]

Add comments to getTestJindoEngineNode in pkg/ddc/jindo/dataset.go
// getTestJindoEngineNode creates and returns a JindoEngine instance for testing.
// It determines whether to initialize runtime-related information based on the withRunTime parameter.
// Parameters:
// - client: Kubernetes client used to interact with API resources.
// - name: Name of the JindoEngine instance.
// - namespace: Namespace where the JindoEngine instance is located.
// - withRunTime: Whether to initialize runtime and runtimeInfo.
//
// Returns:
// - *JindoEngine: The generated JindoEngine instance.。