Remove manually disable field trail feature

Make sure brave/brave-browser#4551 and
#2471 landed first

Author: darkdh

app/brave_main_delegate.cc

@@ -27,7 +27,6 @@
 #include "components/autofill/core/common/autofill_features.h"
 #include "components/autofill/core/common/autofill_payments_features.h"
 #include "components/password_manager/core/common/password_manager_features.h"
-#include "components/sync/driver/sync_driver_switches.h"
 #include "components/unified_consent/feature.h"
 #include "content/public/common/content_features.h"
 #include "extensions/common/extension_features.h"
@@ -148,9 +147,6 @@ bool BraveMainDelegate::BasicStartupComplete(int* exit_code) {
       autofill::features::kAutofillServerCommunication.name,
       features::kAudioServiceOutOfProcess.name,
       features::kDefaultEnableOopRasterization.name,
-      // TODO(darkdh): remove this when USS bookmarks is mature
-      // 84919fdb99b162030a1113d5990667885b774064
-      switches::kSyncUSSBookmarks.name,
       network::features::kNetworkService.name,
       unified_consent::kUnifiedConsent.name,
       features::kLookalikeUrlNavigationSuggestionsUI.name,