sql-server-2014-alwayson-existing-vnet-and-ad is Broken

[SQL Server Always On existing VNET and AD](https://github.com/Azure/azure-quickstart-templates/tree/master/sql-server-2014-alwayson-existing-vnet-and-ad)
### Issue Details

The provided Template is broken! It refers to a non-existing project for nested templates:

https://github.com/Azure/azure-quickstart-templates/tree/master/sql-server-2014-alwayson-dsc

Inspect the sql-server-2014-alwayson-existing-vnet-and-ad template and its reference to sql-server-2014-alwayson-dsc. First verify whether that nested-template path exists in the repository, then identify the intended valid reference. Done means the template no longer points to a missing project and its deployment or validation succeeds.

Written by the indexing model from the issue text.