[Testing] Enable the multi-project template build test

[mattleibow]

In the PR to add a multi-project template:

• Add the multi-project template #20365

The build is failing on CI for some reason:

D:\a_work_temp\test-intg\packages\microsoft.windowsappsdk\1.3.230724000\buildTransitive\Microsoft.UI.Xaml.Markup.Compiler.interop.targets(760,9): error MSB3073: The command ""D:\a_work_temp\test-intg\packages\microsoft.windowsappsdk\1.3.230724000\buildTransitive..\tools\net5.0..\net472\XamlCompiler.exe" "obj\x86\Debug\net8.0-windows10.0.19041.0\win10-x86\input.json" "obj\x86\Debug\net8.0-windows10.0.19041.0\win10-x86\output.json"" exited with code 1. [D:\a_work_temp\test-intg\BuildMultiProjectProjectmauimultiprojectnet80Debug\BuildMultiProjectProjectmauimultiprojectnet80Debug.WinUI\BuildMultiProjectProjectmauimultiprojectnet80Debug.WinUI.csproj]

I am unable to repro locally and get any additional logs.

Binlog for the future:

build-133524013130710969.zip

[ghost]

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