Qt: Don't delete empty achievement images directory

Apparently Windows Defender doesn't like this... this is why I moved
everything out of Documents.

src/duckstation-qt/qthost.cpp

@@ -907,19 +907,8 @@ void QtHost::ApplyMigrations()
   const std::string achievement_icons_directory = Path::Combine(EmuFolders::Cache, "achievement_images");
   if (FileSystem::DirectoryExists(achievement_icons_directory.c_str()))
   {
-    Error error;
-
     // If it's empty, just delete it.
-    if (FileSystem::IsDirectoryEmpty(achievement_icons_directory.c_str()))
-    {
-      if (!FileSystem::DeleteDirectory(achievement_icons_directory.c_str(), &error))
-      {
-        QMessageBox::critical(nullptr, "Error"_L1,
-                              QString::fromStdString(fmt::format(
-                                "Failed to delete empty achievement icons directory: {}", error.GetDescription())));
-      }
-    }
-    else
+    if (!FileSystem::IsDirectoryEmpty(achievement_icons_directory.c_str()))
     {
       QMessageBox mb(
         QMessageBox::Question, "DuckStation"_L1,
@@ -932,6 +921,7 @@ void QtHost::ApplyMigrations()
       mb.setWindowIcon(GetAppIcon());
       if (mb.exec() == QMessageBox::Yes)
       {
+        Error error;
         if (!FileSystem::RecursiveDeleteDirectory(achievement_icons_directory.c_str(), &error))
         {
           QMessageBox::critical(nullptr, "Error"_L1,