Ensure public IP addresses are not assigned to Azure Linux Virtual Machines

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 Virtual Machines.
2. Choose the virtual machine to edit.
3. Under Settings, select Networking, then click on the Network Interface.
4. In the Networking section, under Settings, select IP configurations.
5. Select the interface, then choose Disassociate under Public IP address.
6. Select Save. Note: This does not delete the IP address reservation; to do this, continue below.
7. In the search bar, search for Public IP addresses and go to the corresponding section.
8. Choose the public IP address reservation that was assigned to the interface.
9. Select Delete.

In Terraform -

1. For each azurerm_linux_virtual_machine resource, find the corresponding azurerm_network_interface resource.
2. Remove the public_ip_address_id field.

References:
https://learn.microsoft.com/en-us/azure/virtual-network/network-overview?context=%2Fazure%2Fvirtual-machines%2Fcontext%2Fcontext#network-interfaces
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/linux_virtual_machine
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/network_interface