Update refs to Win2012 since it is out of support

[sdwheeler]

PR Summary

Update refs to Win2012 since it is out of support

• Fixes AB#173407

PR Checklist

• Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• Summary: This PR's summary describes the scope and intent of the change.
• Contributor's Guide: I have read the contributors guide.
• Style: This PR adheres to the style guide.

[learn-build-service-prod]

Learn Build status updates of commit ef521a2:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/5.1/Microsoft.PowerShell.Core/About/about_Run_With_PowerShell.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_Signing.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_Windows_Powershell_5.1.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_Windows_PowerShell_ISE.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Management/Show-ControlPanelItem.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Security/New-FileCatalog.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Security/Set-Acl.md	✅Succeeded	View (powershell-5.1)
reference/7.2/Microsoft.PowerShell.Core/About/about_Run_With_PowerShell.md	✅Succeeded	View (powershell-7.2)
reference/7.2/Microsoft.PowerShell.Core/About/about_Signing.md	✅Succeeded	View (powershell-7.2)
reference/7.2/Microsoft.PowerShell.Security/New-FileCatalog.md	✅Succeeded	View (powershell-7.2)
reference/7.2/Microsoft.PowerShell.Security/Set-Acl.md	✅Succeeded	View (powershell-7.2)
reference/7.3/Microsoft.PowerShell.Core/About/about_Run_With_PowerShell.md	✅Succeeded	View (powershell-7.3)
reference/7.3/Microsoft.PowerShell.Core/About/about_Signing.md	✅Succeeded	View (powershell-7.3)
reference/7.3/Microsoft.PowerShell.Security/New-FileCatalog.md	✅Succeeded	View (powershell-7.3)
reference/7.3/Microsoft.PowerShell.Security/Set-Acl.md	✅Succeeded	View (powershell-7.3)
reference/7.4/Microsoft.PowerShell.Core/About/about_Run_With_PowerShell.md	✅Succeeded	View (powershell-7.4)
reference/7.4/Microsoft.PowerShell.Core/About/about_Signing.md	✅Succeeded	View (powershell-7.4)
reference/7.4/Microsoft.PowerShell.Security/New-FileCatalog.md	✅Succeeded	View (powershell-7.4)
reference/7.4/Microsoft.PowerShell.Security/Set-Acl.md	✅Succeeded	View (powershell-7.4)
reference/docs-conceptual/developer/installing-the-windows-powershell-sdk.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/learn/remoting/jea/prerequisites.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/learn/remoting/PS-remoting-second-hop.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/learn/remoting/WinRMSecurity.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/whats-new/Migrating-from-Windows-PowerShell-51-to-PowerShell-7.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/windows-powershell/install/Windows-PowerShell-System-Requirements.md	✅Succeeded	View (>=powershell-5.1)

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