Disabling xunit AppDomain in System.Configuration.ConfigurationManager in favor of consistent BaseDirectory path behavior (#19546)

* Disabled xunit AppDomain in favor of consistent BaseDirectory behavior

* Activated test again

* Refined XUnitNoAppdomain comment

Author: ViktorHofer

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

@@ -4,6 +4,8 @@
   <PropertyGroup>
     <ProjectGuid>{7669C397-C21C-4C08-83F1-BE6691911E88}</ProjectGuid>
     <TestCategories>InnerLoop;OuterLoop</TestCategories>
+    <!-- XUnit AppDomains BaseDirectory path doesn't contain a trailing slash, which impacts our tests. -->
+    <XUnitNoAppdomain>true</XUnitNoAppdomain>
   </PropertyGroup>
   <!-- Default configurations to help VS understand the options -->
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='netstandard-Debug|AnyCPU'" />

src/System.Configuration.ConfigurationManager/tests/System/Configuration/UrlPathTests.cs

@@ -25,7 +25,6 @@ public void GetDirectoryOrRootName_NotDirectoryOrRoot()
         }
 
         [Fact]
-        [SkipOnTargetFramework(TargetFrameworkMonikers.NetFramework, "dotnet/corefx #18196")]
         public void GetDirectoryOrRootName_GettingDirectoryFromAFilePath()
         {
             string exePath = AppDomain.CurrentDomain.BaseDirectory;