Per-txn does not work on AMD metrics

[hsane-dev]

The pertxn flag has no effect on AMD metrics, needs to add normalization by txn. This will require adding metric definitions where "per txn" is applicable in the metric lists. metrics_defs.go should pick up relevant metrics to normalize:
// swap in per-txn metric definition if transaction rate is provided
if flagTransactionRate != 0 && tmpMetric.ExpressionTxn != "" {
tmpMetric.Expression = tmpMetric.ExpressionTxn
tmpMetric.Expression = strings.ReplaceAll(tmpMetric.Expression, "[TXN]", fmt.Sprintf("%f", flagTransactionRate))
tmpMetric.Name = tmpMetric.NameTxn
}