• This issue is blocking
• This issue is causing unreasonable pain

Context
This is a follow-up for #6975.

Arcade is now dogfooding the .NET SDK and was updated to .NET 6 Preview 1 (#6975).
In DotNetCli.props, we set the version to the ASP.NET Core runtime's version that is contained in this SDK's full version.

Green is the SDK's full version, yellow is the runtime contained inside:

The problem
We construct the URL to get the runtime package like this:

This URL is getting 404 as we put in the version twice. I am not sure what the correct link should be.
This worked before because everything was 5.0.100

What is blocked
Currently, we won't be able to update the dotnet SDK version in the global.json.
To unblock ourselves, we have hardcoded the ASP.NET Core runtime's version to be the major one in so it should work for now but we need a stable flexible solution.

The hardcode places are in DotNetCli.props and XHarnessRunner.targets as per #6975.