Revert "[Sync] Log dropped invalidations in Sync browser tests"

This reverts commit 51ae61cd.

Reason for revert: Reverting some CLs that are suspect for causing
flakiness in the tests

Original change's description:
> [Sync] Log dropped invalidations in Sync browser tests
> 
> This patch adds logging for the dropped invalidations in Sync browser
> tests. This will help investigate some flaky tests.
> 
> Invalidation are dropped if they are received before an
> FCMNetworkHandler is actually assigned and listening for FCM messages.
> 
> 
> Change-Id: I10409bfdda7b0616da6e45a6ecd5f00b3cd5bef0
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1771904
> Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
> Reviewed-by: Marc Treib <treib@chromium.org>
> Reviewed-by: Jan Krcal <jkrcal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#691090}

TBR=treib@chromium.org,jkrcal@chromium.org,mamir@chromium.org

Change-Id: I235908f6977eded9164da806156be5433aca8a83
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1774625Reviewed-by: Mohamed Amir Yosef <mamir@chromium.org>
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691532}

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

@@ -39,10 +39,6 @@ void FakeServerInvalidationSender::OnCommit(
   // FCM network handlers get assigned in SetupInvalidations() which happens
   // after SetupSync().
   if (fcm_network_handler == nullptr) {
-    DLOG(WARNING) << "Received invalidations for the following data types in "
-                     "invalidation sender "
-                  << this << " will be dropped:"
-                  << ModelTypeSetToString(committed_model_types);
     return;
   }
   // For each of the committed model types, pass a message to the FCM Network