Disable flaky DesksMockTimeTest.DeskTraversalNonTouchpadMetrics

TBR=sammiequon@chromium.org, afakhry@chromium.org

Bug: 1151856
Change-Id: Ie131d72ec0f53d26d61aef0f83608fc0990140d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2554538Reviewed-by: Alexander Hendrich <hendrich@chromium.org>
Commit-Queue: Alexander Hendrich <hendrich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#830117}

ash/wm/desks/desks_unittests.cc

@@ -3734,7 +3734,8 @@ class DesksMockTimeTest : public AshTestBase {
   ~DesksMockTimeTest() override = default;
 };
 
-TEST_F(DesksMockTimeTest, DeskTraversalNonTouchpadMetrics) {
+// TODO(crbug.com/1151856) flaky test
+TEST_F(DesksMockTimeTest, DISABLED_DeskTraversalNonTouchpadMetrics) {
   NewDesk();
   NewDesk();
   NewDesk();