Remove dotnet_root from yaml

[nohwnd]

Description

Remove dotnet root that was incorrectly added few minutes ago in #15264

[Youssef1313]

Looks like it's needed:

  You must install or update .NET to run this application.
  
  App: D:\a\_work\1\s\artifacts\bin\Microsoft.TestPlatform.CoreUtilities.UnitTests\Release\net9.0\Microsoft.TestPlatform.CoreUtilities.UnitTests.exe
  Architecture: x64
  Framework: 'Microsoft.NETCore.App', version '9.0.0' (x64)
  .NET location: C:\Program Files\dotnet\
  
  The following frameworks were found:
    8.0.20 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
    10.0.0-rc.1.25451.107 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  You must install or update .NET to run this application.

Probably worked in the past by chance because RC1 seems to be globally installed.