Reduce flackiness of the integration tests

This number reduce count of times the test succeed when it should fail.
I assume this is because of WER doing it's job and process do not exit in time.
Related dotnet#5319

src/System.Windows.Forms/tests/IntegrationTests/System.Windows.Forms.IntegrationTests/WinformsControlsTest.cs

@@ -163,6 +163,7 @@ public void WinformsControlsTest_OpenFolderBrowserDialogTest()
             TestHelpers.SendAltKeyToProcess(process, 'b', switchToMainWindow: false);
             TestHelpers.SendAltKeyToProcess(process, 'o', switchToMainWindow: false);
 
+            System.Threading.Thread.Sleep(2_000);
             Assert.False(process.HasExited);
 
             process.Kill();