is_virtual core fact incorrect on Windows guest on Proxmox

[trenta]

Describe the Bug

Windows guests on Proxmox return false for core fact is_virtual

Expected Behavior

They should return true

Environment

• Puppet Version 8.10.0
• Platform Windows Server 2022

Additional Context

Windows on vmware

Debug: Facter: List of resolvable facts: [#<Facter::SearchedFact:0x000000000a8f3770 @name="is_virtual", @fact_class=Facts::Windows::IsVirtual, @user_query="is_virtual", @type=:core, @file=nil>]
Debug: Facter: fact "is_virtual" has resolved to: true
{
  "is_virtual": true
}

Windows on proxmox

Debug: Facter: List of resolvable facts: [#<Facter::SearchedFact:0x0000000009bd8400 @name="is_virtual", @fact_class=Facts::Windows::IsVirtual, @user_query="is_virtual", @type=:core, @file=nil>]
Debug: Facter: fact "is_virtual" has resolved to: false
{
  "is_virtual": false
}

Linux on proxmox

Debug: Facter: Executing command: virt-what
Debug: Facter: fact "is_virtual" has resolved to: true
{
  "is_virtual": true
}

[austb]

Linking this to its slack thread https://puppetcommunity.slack.com/archives/C0W298S9G/p1731453036716109

the system info looked like this (when the QEMU guest agent was installed)

 Get-WmiObject -Class Win32_ComputerSystem | Select-Object Manufacturer, Model, OEMStringArray

Manufacturer Model                          OEMStringArray
------------ -----                          --------------
QEMU         Standard PC (Q35 + ICH9, 2009)

It would be worth looking into if we can detect this virtualization without that installed as well https://pve.proxmox.com/wiki/Qemu-guest-agent