Remove EventListener crash workaround

We've turned off AppDomain isolation in https://github.com/dotnet/roslyn/pull/8672 and https://github.com/dotnet/roslyn/pull/8534.

src/Scripting/CSharpTest.Desktop/CSharpScriptingTest.Desktop.csproj

@@ -29,7 +29,6 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="CsiTests.cs" />
-    <Compile Include="EventListenerCrash_Workaround.cs" />
     <Compile Include="InteractiveSessionTests.cs" />
     <Compile Include="ObjectFormatterTests.cs" />
   </ItemGroup>

src/Scripting/CSharpTest.Desktop/EventListenerCrash_Workaround.cs

-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-
-using System.Threading;
-using Xunit;
-
-namespace Microsoft.CodeAnalysis.Scripting.Test
-{
-    // xunit is crashing due to a bug in the CLR, see:https://github.com/dotnet/roslyn/issues/6358.
-    //
-    // This issue tends to occur more often on test binaries with 
-    // very short running tests. This class solely exists to avoid hitting
-    // it, and can be deleted when more tests are added to the assembly 
-    // or when the CLR bug is fixed.
-    public class EventListenerCrash_Workaround
-    {
-        [Fact]
-        public void WaitFor10Seconds()
-        {
-            // Wait for ten seconds
-            Thread.Sleep(10000);
-        }
-    }
-}

src/Scripting/CoreTest.Desktop/EventListenerCrash_Workaround.cs

-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-
-using System.Threading;
-using Xunit;
-
-namespace Microsoft.CodeAnalysis.Scripting.Test
-{
-    // xunit is crashing due to a bug in the CLR, see:https://github.com/dotnet/roslyn/issues/6358.
-    //
-    // This issue tends to occur more often on test binaries with 
-    // very short running tests. This class solely exists to avoid hitting
-    // it, and can be deleted when more tests are added to the assembly 
-    // or when the CLR bug is fixed.
-    public class EventListenerCrash_Workaround
-    {
-        [Fact]
-        public void WaitFor10Seconds()
-        {
-            // Wait for ten seconds
-            Thread.Sleep(10000);
-        }
-    }
-}

src/Scripting/CoreTest.Desktop/ScriptingTest.Desktop.csproj

@@ -54,7 +54,6 @@
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
   </PropertyGroup>
   <ItemGroup>
-    <Compile Include="EventListenerCrash_Workaround.cs" />
     <Compile Include="GlobalAssemblyCacheTests.cs" />
     <Compile Include="MetadataShadowCopyProviderTests.cs" />
   </ItemGroup>