[AnomalyDetection] Some points marked as anomaly with little deviation

### System information

- **OS version/distro**:
- **.NET Version (eg., dotnet --info)**: master

### Issue

- **What did you do?** Apply AnomalyDetection API
- **What happened?** Some points are marked as anomaly while some others that look more like anomaly are not marked as anomaly.
- **What did you expect?** I expect the points that look has more deviations mark as anomaly, rather than the ones with small deviation.

Expecting the highlighted points with higher deviation to be anomalies.

**Please assign the issue** to: https://github.com/guinao and https://github.com/mengaims

### Source code / logs

var anomalyDetectorOptions = new SrCnnEntireAnomalyDetectorOptions()
{
DetectMode = //WithMargin,
Sensitivity = 20,
DeseasonalityMode = SrCnnDeseasonalityMode.Median,
Period = -1,
Threshold =0.18,
};

anomalyResult = this.mlContext.AnomalyDetection.DetectEntireAnomalyBySrCnn(
...
anomalyDetectorOptions);