Remove obsolete WebListener test scenario

test/AutobahnTestApp/Startup.cs

@@ -15,15 +15,6 @@ public class Startup
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
         public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
         {
-            if (!env.IsEnvironment("NativeSockets"))
-            {
-                // Register a middleware that disables the server-provided WebSockets feature
-                app.Use((context, next) =>
-                {
-                    context.Features.Set<IHttpWebSocketFeature>(null);
-                    return next();
-                });
-            }
             app.UseWebSockets();
 
             app.Use(async (context, next) =>

test/Microsoft.AspNetCore.WebSockets.ConformanceTest/AutobahnTests.cs

@@ -75,9 +75,6 @@ await tester.DeployTestAndAddToSpec(ServerType.WebListener, ssl: false, environm
                     }
                 }
 
-                // REQUIRES a build of WebListener that supports native WebSockets, which we don't have right now
-                //await tester.DeployTestAndAddToSpec(ServerType.WebListener, ssl: false, environment: "NativeSockets");
-
                 result = await tester.Run(cts.Token);
                 tester.Verify(result);
             }