database import from bacpac failed. "'Origin.xml' is missing from the dacpac package."

[XSS attack on a web app](https://github.com/Azure/azure-quickstart-templates/tree/master/demos/xss-attack-prevention)

### Issue Details

database importing from bacpac is failed.

```
{
"status": "Failed",
"error": {
"code": "BadRequest",
"message": "The ImportExport operation with Request Id 'd8610a1e-5463-4acf-ae24-d1f5a2233706' failed due to ''Origin.xml' is missing from the dacpac package. Could not load package.'.",
"details": []
}
}
```

### Repro steps (*if necessary, delete otherwise*)
1. download zipfile from repo. https://github.com/Azure/azure-quickstart-templates/blob/master/demos/xss-attack-prevention/artifacts/ContosoClinic.zip
2. put zip file into azure blob storage
3. deploy template with url of the zip file at bacpacuri parameter.

Start with demos/xss-attack-prevention/artifacts/ContosoClinic.zip and the deployment template's bacpacuri parameter, then reproduce the import using the linked blob URL. Inspect why the package is rejected for missing Origin.xml; done means the template deployment imports the database successfully without that error.

Written by the indexing model from the issue text.