Revert "Re-enable AccountManagerUIHandlerTest tests"

This reverts commit ceada96f.

Reason for revert: The tests are still flaky. e.g. https://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=AccountManagerUIHandlerTestSuite%2FAccountManagerUIHandlerTest.OnGetAccountsWithSecondaryAccounts%2F0&testType=browser_tests

Original change's description:
> Re-enable AccountManagerUIHandlerTest tests
>
> AccountManagerUIHandlerTest tests were disabled in
> https://bugs.chromium.org/p/chromium/issues/detail?id=1131834
> due to flakiness with ExternalWebAppManager. This is due to
> https://chromium-review.googlesource.com/c/chromium/src/+/2423823
> altering the behaviour of when
> chromeos::ProfileHelper::IsPrimaryProfile() gets called uncovering
> an incompatiblity between the profile created by these tests and
> IsPrimaryProfile().
>
> This CL disables ExternalWebAppManager's start up flow to avoid
> triggering the IsPrimaryProfile() incompatibility so we can
> re-enable these tests.
>
> Bug: 1131834
> Change-Id: Ia4d15785a64b45689f742d3604c10e1b8502cafd
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2434412
> Auto-Submit: Alan Cutter <alancutter@chromium.org>
> Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
> Commit-Queue: Alan Cutter <alancutter@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#811404}

TBR=michaelpg@chromium.org,alancutter@chromium.org

Change-Id: I6b783ce2797fd5e88e5a1a131782a1598ab2f1b9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1131834
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2437171Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811669}

chrome/browser/ui/webui/settings/chromeos/account_manager_handler_browsertest.cc

@@ -14,7 +14,6 @@
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
 #include "chrome/browser/signin/identity_manager_factory.h"
 #include "chrome/browser/supervised_user/supervised_user_constants.h"
-#include "chrome/browser/web_applications/external_web_app_manager.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/testing_profile.h"
 #include "chromeos/components/account_manager/account_manager.h"
@@ -127,11 +126,6 @@ class AccountManagerUIHandlerTest
       delete;
 
   void SetUpOnMainThread() override {
-    // Disable preinstalled app scan, it is not compatible with the testing
-    // profile we create here.
-    // TODO(crbug.com/1131834): Make it compatible.
-    web_app::ExternalWebAppManager::SkipStartupForTesting();
-
     user_manager_enabler_ = std::make_unique<user_manager::ScopedUserManager>(
         std::make_unique<chromeos::FakeChromeUserManager>());
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
@@ -232,8 +226,9 @@ class AccountManagerUIHandlerTest
   std::unique_ptr<TestingAccountManagerUIHandler> handler_;
 };
 
+// TODO(https://crbug.com/1131834): Re-enable flaky test.
 IN_PROC_BROWSER_TEST_P(AccountManagerUIHandlerTest,
-                       OnGetAccountsNoSecondaryAccounts) {
+                       DISABLED_OnGetAccountsNoSecondaryAccounts) {
   const std::vector<AccountManager::Account> account_manager_accounts =
       GetAccountsFromAccountManager();
   // Only Primary account.
@@ -276,8 +271,9 @@ IN_PROC_BROWSER_TEST_P(AccountManagerUIHandlerTest,
   }
 }
 
+// TODO(https://crbug.com/1131819): Re-enable flaky test.
 IN_PROC_BROWSER_TEST_P(AccountManagerUIHandlerTest,
-                       OnGetAccountsWithSecondaryAccounts) {
+                       DISABLED_OnGetAccountsWithSecondaryAccounts) {
   UpsertAccount("secondary1@example.com");
   UpsertAccount("secondary2@example.com");
   const std::vector<AccountManager::Account> account_manager_accounts =