Revert "[WebAppProvider] Fix test flakiness for AppSorting."

This reverts commit ce6e5f49.

Reason for revert: the test is now flaky. See details in https://crbug.com/1099615

Original change's description:
> [WebAppProvider] Fix test flakiness for AppSorting.
> 
> The test waits for both installations, but this can be flaky as waiting
> for the first installation could hide the second installation. So when
> it waits for the second installation, it already happened.
> 
> This fix only waits for the second installation to prevent this race
> from happening.
> 
> R=​loyso@chromium.org
> 
> Change-Id: I57549f0d1be11e980ecebc6ba7fb8d2ec4e0b7be
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2268180
> Auto-Submit: Daniel Murphy <dmurph@chromium.org>
> Reviewed-by: Alexey Baskakov <loyso@chromium.org>
> Reviewed-by: Chase Phillips <cmp@chromium.org>
> Commit-Queue: Alexey Baskakov <loyso@chromium.org>
> Commit-Queue: Daniel Murphy <dmurph@chromium.org>
> Commit-Queue: Chase Phillips <cmp@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#782775}

TBR=cmp@chromium.org,dmurph@chromium.org,loyso@chromium.org

Change-Id: I69984efe4b14b967eeccc4a59f617725bd648339
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1099615
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2270178Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782895}

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

@@ -436,7 +436,9 @@ IN_PROC_BROWSER_TEST_F(TwoClientWebAppsBMOSyncTest, AppSortingFixCollisions) {
       GetProfile(0), WebappInstallSource::OMNIBOX_INSTALL_ICON,
       GetUserInitiatedAppURL2());
 
-  // Wait for the second install (as they install in order).
+  // Wait for both installs.
+  EXPECT_EQ(WebAppInstallObserver(GetProfile(1), app_id1).AwaitNextInstall(),
+            app_id1);
   EXPECT_EQ(WebAppInstallObserver(GetProfile(1), app_id2).AwaitNextInstall(),
             app_id2);
   EXPECT_TRUE(AllProfilesHaveSameWebAppIds());