Related to #1948:

This property needs to be propagated to repo builds when building the VMR. Without it, test signing cannot be performed, rendering the Signed (Test) parameter ineffective. Note that this does not affect real signing, which still functions as long as OfficialBuild is set and DryRun signing is not enabled, as outlined here: https://github.com/dotnet/arcade/blob/aec4b170fd6d0490f12c4b51607f55df3622076e/src/Microsoft.DotNet.Arcade.Sdk/tools/Sign.proj#L53