[Sheriff] Disable flaky ChromeVoxBackgroundTest.SelectSingleBasic

TBR=akihiroota

Bug: 1042673
Change-Id: Iccf2064ee5b817bc9e7f12c026cd8569e39d22b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2002816Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732396}

chrome/browser/resources/chromeos/accessibility/chromevox/background/background_test.js

@@ -262,7 +262,8 @@ TEST_F(
       });
     });
 
-TEST_F('ChromeVoxBackgroundTest', 'SelectSingleBasic', function() {
+// Flaky: https://crbug.com/1042673
+TEST_F('ChromeVoxBackgroundTest', 'DISABLED_SelectSingleBasic', function() {
   var mockFeedback = this.createMockFeedback();
   this.runWithLoadedTree(this.formsDoc, function() {
     mockFeedback.expectSpeech('apple', 'has pop up', 'Collapsed')