Fixes #4374 - Nukes all (?) legacy Driver and Application stuff; revamps tests (#4376)

Tests/UnitTestsParallelizable/Configuration/ScopeTests.cs

@@ -226,7 +226,9 @@ public class ScopeTests
                                  }));
         }
 
+#pragma warning disable xUnit1031
         Task.WaitAll (tasks.ToArray ());
+#pragma warning restore xUnit1031
 
         // Assert
         Assert.Equal (threadCount * itemsPerThread, scope.Count);