Update VM image to Windows Server 2025 Datacenter

Author: msftnutta

Instructions/Exercises/M04-Unit 4 Create and configure an Azure load balancer.md

@@ -227,7 +227,7 @@ In this section, you will create a test VM, and then test the load balancer.
    | Virtual machine name | **myTestVM**                                 |
    | Region               | **(US) East US**                             |
    | Availability options | **No infrastructure redundancy required**    |
-   | Image                | **Windows Server 2019 Datacenter - Gen 2**   |
+   | Image                | **Windows Server 2025 Datacenter Server Core - x64 Gen 2**   |
    | Size                 | **Standard_DS2_v3 - 2 vcpu, 8 GiB memory**   |
    | Username             | **TestUser**                                 |
    | Password             | **Provide a secure password**                |