Retry preset migration when login warmup 401 blocks cloud check (#14049)

src/slic3r/GUI/GUI_App.hpp

@@ -324,6 +324,7 @@ private:
     std::shared_ptr<int> m_user_sync_token;
     std::atomic<bool>    m_restart_sync_pending {false};
     std::atomic<bool>    m_sync_user_presets_now {false}; // request the sync loop to push user presets on its next tick
+    std::atomic<bool>    m_migration_retry_pending {false};
     bool             m_is_dark_mode{ false };
     bool             m_adding_script_handler { false };
     bool             m_side_popup_status{false};