- correct Helix test failures with stable versions, where SDK's packs aren't enough
E.g. from https://dev.azure.com/dnceng/internal/_build/results?buildId=813814
``` text
...\.dotnet\sdk\5.0.100-rc.1.20379.10\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(318,5): error MSB4018: The "ResolveTargetingPackAssets" task failed unexpectedly. [...\src\ProjectTemplates\test\bin\Release\net5.0\TestTemplates\AspNet.m0yq3xrporu\AspNet.m0yq3xrporu.csproj]
...\.dotnet\sdk\5.0.100-rc.1.20379.10\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(318,5): error MSB4018: System.IO.DirectoryNotFoundException: Could not find a part of the path '...\.dotnet\packs\Microsoft.AspNetCore.App.Ref\5.0.0\data\FrameworkList.xml'. [...\src\ProjectTemplates\test\bin\Release\net5.0\TestTemplates\AspNet.m0yq3xrporu\AspNet.m0yq3xrporu.csproj]
```
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