code: func getSplitCount(numFeedbacks, remainBuckets int) int {
  	// Split more if have more buckets available.
  	splitCount := mathutil.Max(remainBuckets, defaultSplitCount)
  	return mathutil.Min(splitCount, numFeedbacks/splitPerFeedback)
  }
docs: // getSplitCount gets the split count for the histogram. It is based on the intuition that:
  // 1: If we have more remaining unused buckets, we can split more.
  // 2: We cannot split too aggressive, thus we make it split every `splitPerFeedback`.