Template "Deploy a Highly Available NFS Cluster with Ubuntu VMs" will not finish if dataDiskSizeInGB > 256 GB

[Deploy a Highly Available NFS Cluster with Ubuntu VM](https://github.com/Azure/azure-quickstart-templates/tree/master/nfs-ha-cluster-ubuntu)

### Issue Details
The template works perfectly if the size of the disk is set to 256GB. (parameter: dataDiskSizeInGB). If you set the value to > 256 GB, like 512GB or more it will fail as the extension will not finish.

### Repro steps (*if necessary, delete otherwise*)
1. In the parameters file for the template define the param: dataDiskSizeInGB to value higher than 256GB
2. deploy the template into Azure (I have deployed the template to West Europe and North Europe)
3. the template will not finish deployment in around 1.5h and then it will report failure, however, it may happen that the service will function properly

Start with the nfs-ha-cluster-ubuntu template linked in the issue and inspect how dataDiskSizeInGB is used during deployment. Deploy once at 256 GB and once above 256 GB, such as 512 GB, then examine the extension behavior and deployment result. Done means the template completes successfully for disks larger than 256 GB.

Written by the indexing model from the issue text.