Ensure public access is disabled for Azure Storage Sync

Allowing unrestricted, public access to cloud services could open an application up to external attack. Disallowing this access is typically considered best practice.

In Azure Console -

1. Open the Azure Portal and go to Storage Sync Services.
2. Select the Storage Sync that you wish to edit.
3. Under Settings, select Network.
4. Create a private endpoint and set the Allow access from setting to Private endpoints only.

In Terraform -

1. In the azurerm_storage_management_policy resource, remove an incoming_traffic_policy field that's set to AllowAllTraffic or replace the value with AllowVirtualNetworksOnly.

References:
https://learn.microsoft.com/en-us/azure/storage/blobs/snapshots-overview
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/storage_sync