Enable razor in unified-build (#18776)

Co-authored-by: Eric StJohn <ericstj@microsoft.com>

src/SourceBuild/content/repo-projects/Directory.Build.targets

@@ -322,8 +322,6 @@
                             UpdateEngCommonFiles;
                             CreateBuildInputProps;
                             SetSourceBuiltSdkOverrides">
-    <Exec Command="$(DotnetTool) build-server shutdown" />
-
     <Message Importance="High" Text="[$([System.DateTime]::Now.ToString('HH:mm:ss.ff'))] Building $(RepositoryName)" />
     <Message Importance="High" Text="Running command:" />
     <Message Importance="High" Text="  $(BuildCommand)" />
@@ -737,7 +735,6 @@
       <TransitiveRepositoryReference Remove="roslyn" />
       <TransitiveRepositoryReference Remove="msbuild" />
       <TransitiveRepositoryReference Remove="aspnetcore" />
-      <TransitiveRepositoryReference Remove="razor" />
       <TransitiveRepositoryReference Remove="nuget-client" />
       <TransitiveRepositoryReference Remove="fsharp" />
       <TransitiveRepositoryReference Remove="vstest" />

src/SourceBuild/content/repo-projects/arcade.proj

@@ -15,11 +15,6 @@
     <BuiltSdkPackageOverride Include="@(ArcadeCMakeSdkOverride)" />
   </ItemGroup>
 
-  <ItemGroup>
-    <EnvironmentVariables Include="UsingToolMicrosoftNetCompilers=false" />
-    <EnvironmentVariables Include="useInstalledDotNetCli=false" />
-  </ItemGroup>
-
   <ItemGroup>
     <ExtraPackageVersionPropsPackageInfo Include="NuGetVersion" Version="%24(NuGetPackagingVersion)" />
   </ItemGroup>

src/SourceBuild/content/repo-projects/razor.proj

@@ -1,5 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
+  <PropertyGroup>
+    <!-- The toolset compiler doesn't get killed with 'build-server shutdown'.
+         Instead of disabling shared compilation, disable the toolset compiler package. -->
+    <BuildArgs>$(BuildArgs) /p:UsingToolMicrosoftNetCompilers=false</BuildArgs>
+  </PropertyGroup>
+
   <ItemGroup>
     <RepositoryReference Include="arcade" />
   </ItemGroup>