lack of setting new value for pullThresholdSizeForTopic after size was calc.

[ShannonDing]

after rebalance, PullThresholdSizeForTopic is not set to new value.

if count > 0 {
		if pc.option.PullThresholdForTopic != -1 {
			newVal := pc.option.PullThresholdForTopic / count
			if newVal == 0 {
				newVal = 1
			}
			rlog.Info("The PullThresholdForTopic is changed", map[string]interface{}{
				rlog.LogKeyValueChangedFrom: pc.option.PullThresholdForTopic,
				rlog.LogKeyValueChangedTo:   newVal,
			})
			pc.option.PullThresholdForTopic = newVal
		}

		if pc.option.PullThresholdSizeForTopic != -1 {
			newVal := pc.option.PullThresholdSizeForTopic / count
			if newVal == 0 {
				newVal = 1
			}
			rlog.Info("The PullThresholdSizeForTopic is changed", map[string]interface{}{
				rlog.LogKeyValueChangedFrom: pc.option.PullThresholdSizeForTopic,
				rlog.LogKeyValueChangedTo:   newVal,
			})
		}
	}