Remove project dependency in S.Configuration.Tests.csproj (#74016)

Reference is not needed; was causing build issues for some platforms.

Fixes #73792

Author: steveharter

src/libraries/System.Configuration.ConfigurationManager/tests/System.Configuration.ConfigurationManager.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <IncludeRemoteExecutor>true</IncludeRemoteExecutor>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetFrameworkMinimum)</TargetFrameworks>
@@ -97,9 +97,6 @@
   <ItemGroup>
     <ProjectReference Include="..\src\System.Configuration.ConfigurationManager.csproj" />
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
-      <ProjectReference Include="$(LibrariesProjectRoot)System.Diagnostics.TraceSource\src\System.Diagnostics.TraceSource.csproj" />
-  </ItemGroup>
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">
     <Reference Include="System.Configuration" />
     <!-- Manually reference the transitive dependency to make NuGet pick the package over the transitive project: https://github.com/NuGet/Home/issues/10368 -->

src/libraries/tests.proj

@@ -339,11 +339,6 @@
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.Security/tests/FunctionalTests/System.Net.Security.Tests.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetOS)' == 'Android' or '$(TargetOS)' == 'iOS' or '$(TargetOS)' == 'iOSSimulator' or '$(TargetOS)' == 'tvOS' or '$(TargetOS)' == 'tvOSSimulator' or '$(TargetOS)' == 'MacCatalyst'">
-    <!-- Build error: https://github.com/dotnet/runtime/issues/73792 -->
-    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Configuration.ConfigurationManager/tests/System.Configuration.ConfigurationManager.Tests.csproj" />
-  </ItemGroup>
-
   <ItemGroup Condition="'$(TargetOS)' == 'Browser' and '$(RunDisabledWasmTests)' != 'true' and '$(RunAOTCompilation)' != 'true'">
   </ItemGroup>