Refactor GetLoggingConfig method

[Cali0707]

We have the same function public in cmd/broker:

eventing/cmd/broker/config.go

Lines 30 to 38 in e804605

	func GetLoggingConfig(ctx context.Context, namespace, loggingConfigMapName string) (*logging.Config, error) {
	loggingConfigMap, err := kubeclient.Get(ctx).CoreV1().ConfigMaps(namespace).Get(ctx, loggingConfigMapName, metav1.GetOptions{})
	if apierrors.IsNotFound(err) {
	return logging.NewConfigFromMap(nil)
	} else if err != nil {
	return nil, err
	}
	return logging.NewConfigFromConfigMap(loggingConfigMap)
	}

. Could be reused (but can be done in a follow up PR, as other cmds might have the same)

Originally posted by @creydr in #8699 (comment)

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[creydr]

/remove-lifecycle stale