[Premium] Max pre-warmed instances

**Describe the bug**
When configuring the pre-warmed instance count of the elastic scale, it cannot have values >10.
I get the following error message:
`PreWarmedInstanceCount must be greater than zero and less than 10.`

**To Reproduce**
```http
PATCH https://management.azure.com/subscriptions//resourceGroups//providers/Microsoft.Web/sites//config/web?api-version=2018-11-01
Authorization:
Content-Type: application/json

{
"id": "//resourceGroups//providers/Microsoft.Web/sites//config/web",
"name": "",
"type": "Microsoft.Web/sites/config",
"location": "",
"properties": {
"reservedInstanceCount": 11,
"functionsRuntimeScaleMonitoringEnabled": false
}
}

```
Or go to `Functions App -> Platform Feature -> Scale-Out` and set the slider to 11 and click save.

**Expected behavior**
It sets the value to 11.