Turn off "All Bookmarks" completely. Finally.

ios/chrome/browser/experimental_flags.mm

Index: ios/chrome/browser/experimental_flags.mm
diff --git a/ios/chrome/browser/experimental_flags.mm b/ios/chrome/browser/experimental_flags.mm
index e8932de1189e242391c9de3c097c09422b3a0992..fa9b1f13324d0dc928d529da88f7877577884842 100644
--- a/ios/chrome/browser/experimental_flags.mm
+++ b/ios/chrome/browser/experimental_flags.mm
@@ -117,7 +117,7 @@ bool IsAllBookmarksEnabled() {
       base::FieldTrialList::FindFullName("RemoveAllBookmarks");
 
   if (group_name.empty()) {
-    return true;  // If no finch experiment, keep all bookmarks enabled.
+    return false;  // If no finch experiment, all bookmarks is disabled.
   }
   return base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);