use SpecialFolder.UserProfile instead of USERPROFILE (#15135)

Co-authored-by: Alexander Köplinger <alex.koeplinger@outlook.com>

Author: kasperk81

src/Microsoft.DotNet.XUnitConsoleRunner/src/common/AssemblyResolution/Microsoft.Extensions.DependencyModel/Resolution/PackageCompilationAssemblyResolver.cs

@@ -56,23 +56,13 @@ internal static string[] GetDefaultProbeDirectories(Platform osPlatform, IEnviro
                return new string[] { packageDirectory };
            }
 
-           string basePath;
-           if (osPlatform == Platform.Windows)
-           {
-               basePath = environment.GetEnvironmentVariable("USERPROFILE");
-           }
-           else
-           {
-               basePath = environment.GetEnvironmentVariable("HOME");
-           }
-
+           string basePath = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
            if (string.IsNullOrEmpty(basePath))
            {
                return new string[] { string.Empty };
            }
 
            return new string[] { Path.Combine(basePath, ".nuget", "packages") };
-
         }
 
         public bool TryResolveAssemblyPaths(CompilationLibrary library, List<string> assemblies)

src/Microsoft.DotNet.XUnitConsoleRunner/src/common/AssemblyResolution/XunitPackageCompilationAssemblyResolver.cs

@@ -44,12 +44,7 @@ static List<string> GetDefaultProbeDirectories(Platform osPlatform, IMessageSink
                     results.Add(packageDirectory);
                 else
                 {
-                    string basePath;
-                    if (osPlatform == Platform.Windows)
-                        basePath = Environment.GetEnvironmentVariable("USERPROFILE");
-                    else
-                        basePath = Environment.GetEnvironmentVariable("HOME");
-
+                    string basePath = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
                     if (!string.IsNullOrEmpty(basePath))
                         results.Add(Path.Combine(basePath, ".nuget", "packages"));
                 }