Fix storage backups for Azure clusters

[GeorgianaElena]

This is a follow-up to #624 and is blocking #4426

While working on validating that restoring backups works, I couldn't find any backup instances, so we need to figure out what's missing to get that working.

• Check if https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/backup_protected_file_share is the missing bit
• Verify that a backup is actually created