Disable flaky test: TwoClientSendTabToSelfSyncTest.SendTabToSelfReceivingDisabled.

This test seems to be flaking more frequently as of late. Disabling it
to reduce jank on the bots.

TBR=tgupta@chromium.org

Bug: 1023950
Change-Id: Iad61dfb317f4bec5b0278c038c1e44c6b912e9e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1913104Reviewed-by: James MacLean <wjmaclean@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714683}

chrome/browser/sync/test/integration/two_client_send_tab_to_self_sync_test.cc

@@ -155,8 +155,9 @@ IN_PROC_BROWSER_TEST_F(TwoClientSendTabToSelfSyncTest,
   EXPECT_TRUE(device_infos[1]->send_tab_to_self_receiving_enabled());
 }
 
+// Flaky. https://crbug.com/1023950
 IN_PROC_BROWSER_TEST_F(TwoClientSendTabToSelfSyncTest,
-                       SendTabToSelfReceivingDisabled) {
+                       DISABLED_SendTabToSelfReceivingDisabled) {
   ASSERT_TRUE(SetupSync());
   GetClient(0)->DisableSyncForType(syncer::UserSelectableType::kTabs);