[AF] Fix flakiness in integration tests for server address metadata sync

This is a speculative fix of rare flakiness. Before this CL, in rare
cases, each client would have a different fake time value. Combined with
another rare race condition in converting server addresses to local
addresses, it would result in initial sync never converging.

Bug: 911953
Change-Id: Ic628cac80b0ffd8977bb29fa5948109366801803
Reviewed-on: https://chromium-review.googlesource.com/c/1373843
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615939}

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

@@ -56,10 +56,10 @@ class TwoClientWalletSyncTest : public UssWalletSwitchToggler, public SyncTest {
   bool TestUsesSelfNotifications() override { return false; }
 
   bool SetupSync() override {
+    test_clock_.SetNow(kArbitraryDefaultTime);
     if (!SyncTest::SetupSync()) {
       return false;
     }
-    test_clock_.SetNow(kArbitraryDefaultTime);
 
     // Plug in SyncService into PDM so that it can check we use full sync.
     GetPersonalDataManager(0)->OnSyncServiceInitialized(GetSyncService(0));