Add-AzureRMMetricsAlertRule timeAggregationOperator param not effective

### Description

The alerts created using Add-AzureRMMetricsAlertRule cmdlet does not reflect the time aggregator parameter passed in (Total,Average,Min,Max..) The default is Average and seems it does not enable us to do otherwise aggregation

I don't see either the option in Azure Portal for selecting aggregation method over time window in Application insight alerts

```powershell
Add-AzureRMMetricsAlertRule -TimeAggregationOperator Total
```

### Module Version

ModuleType Version Name ExportedCommands
---------- ------- ---- ----------------
Manifest 4.0.0 AzureRM.Insights

```powershell
Get-Module -Name AzureRM -ListAvailable
```

### Environment Data
pwsh version: windows
5.1.16299.431

```powershell
$PSVersionTable
```

### Debug Output

```

```