Disabled flaky test: ShowOfflineSetupOptionOnNetworkList.

Disabling flaky test:
DemoSetupArcSupportedTest.ShowOfflineSetupOptionOnNetworkList

Bug: 1099402
Change-Id: I5f8dc26198f3e6fb0e3a7f4f0da4c69e2f93a5cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2268297Reviewed-by: Aga Wronska <agawronska@chromium.org>
Commit-Queue: Chris Mumford <cmumford@google.com>
Cr-Commit-Position: refs/heads/master@{#782708}

chrome/browser/chromeos/login/demo_mode/demo_setup_browsertest.cc

@@ -1156,8 +1156,9 @@ IN_PROC_BROWSER_TEST_F(DemoSetupArcSupportedTest, RetryOnErrorScreen) {
   OobeScreenWaiter(GaiaView::kScreenId).Wait();
 }
 
+// Test is flaky: crbug.com/1099402
 IN_PROC_BROWSER_TEST_F(DemoSetupArcSupportedTest,
-                       ShowOfflineSetupOptionOnNetworkList) {
+                       DISABLED_ShowOfflineSetupOptionOnNetworkList) {
   auto* const wizard_controller = WizardController::default_controller();
   wizard_controller->SimulateDemoModeSetupForTesting();
   SimulateOfflineEnvironment();