Eliminate duplicates in Helix TestRunner

- do not add source that's already in NuGet.config
  - configuration file now part of Helix content
- do not set env variable set in `runtests.*`

nit: simplify `%Path% setting in runtests.cmd
- always quote the value

Author: dougbu

eng/helix/content/RunTests/TestRunner.cs

@@ -34,7 +34,6 @@ public bool SetupEnvironment()
                 }
 
                 EnvironmentVariables.Add("PATH", Options.Path);
-                EnvironmentVariables.Add("DOTNET_ROOT", Options.DotnetRoot);
                 EnvironmentVariables.Add("helix", Options.HelixQueue);
 
                 Console.WriteLine($"Current Directory: {Options.HELIX_WORKITEM_ROOT}");
@@ -126,14 +125,6 @@ await ProcessUtil.RunAsync($"{Options.DotnetRoot}/dotnet",
                         throwOnError: false,
                         cancellationToken: new CancellationTokenSource(TimeSpan.FromMinutes(2)).Token);
 
-                    await ProcessUtil.RunAsync($"{Options.DotnetRoot}/dotnet",
-                        "nuget add source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json --configfile NuGet.config",
-                        environmentVariables: EnvironmentVariables,
-                        outputDataReceived: Console.WriteLine,
-                        errorDataReceived: Console.Error.WriteLine,
-                        throwOnError: false,
-                        cancellationToken: new CancellationTokenSource(TimeSpan.FromMinutes(2)).Token);
-
                     // Write nuget sources to console, useful for debugging purposes
                     await ProcessUtil.RunAsync($"{Options.DotnetRoot}/dotnet",
                         "nuget list source",
@@ -199,8 +190,7 @@ public async Task<bool> InstallDotnetDump()
             try
             {
                 await ProcessUtil.RunAsync($"{Options.DotnetRoot}/dotnet",
-                            $"tool install dotnet-dump --tool-path {Options.HELIX_WORKITEM_ROOT} " +
-                              "--version 5.0.0-* --add-source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json",
+                            $"tool install dotnet-dump --tool-path {Options.HELIX_WORKITEM_ROOT} --version 5.0.0-*",
                             environmentVariables: EnvironmentVariables,
                             outputDataReceived: Console.WriteLine,
                             errorDataReceived: Console.Error.WriteLine,
@@ -247,7 +237,7 @@ public async Task<int> RunTestsAsync()
             {
                 // Timeout test run 5 minutes before the Helix job would timeout
                 var cts = new CancellationTokenSource(Options.Timeout.Subtract(TimeSpan.FromMinutes(5)));
-                var commonTestArgs = $"test {Options.Target} --logger:xunit --logger:\"console;verbosity=normal\" --blame \"CollectHangDump;TestTimeout=5m\"";                
+                var commonTestArgs = $"test {Options.Target} --logger:xunit --logger:\"console;verbosity=normal\" --blame \"CollectHangDump;TestTimeout=5m\"";
                 if (Options.Quarantined)
                 {
                     Console.WriteLine("Running quarantined tests.");
@@ -346,7 +336,7 @@ public void UploadResults()
             else
             {
                 Console.WriteLine("No dmps found in TestResults");
-            }            
+            }
         }
     }
 }

eng/helix/content/runtests.cmd

@@ -1,6 +1,4 @@
 @echo off
-REM Need delayed expansion !PATH! so parens in the path don't mess up the parens for the if statements that use parens for blocks
-setlocal enabledelayedexpansion
 
 REM Use '$' as a variable name prefix to avoid MSBuild variable collisions with these variables
 set $target=%1
@@ -26,8 +24,8 @@ set DOTNET_SKIP_FIRST_TIME_EXPERIENCE=1
 set DOTNET_MULTILEVEL_LOOKUP=0
 set DOTNET_CLI_HOME=%HELIX_CORRELATION_PAYLOAD%\home
 
-set PATH=%DOTNET_ROOT%;!PATH!;%HELIX_CORRELATION_PAYLOAD%\node\bin
-echo Set path to: %PATH%
+set "PATH=%DOTNET_ROOT%;%PATH%;%HELIX_CORRELATION_PAYLOAD%\node\bin"
+echo Set path to: "%PATH%"
 
 powershell.exe -noLogo -NoProfile -ExecutionPolicy unrestricted -command ". eng\common\tools.ps1; InstallDotNet %DOTNET_ROOT% %$sdkVersion% %$arch% '' $true '' '' $true"
 IF [%$feedCred%] == [] (