HackStudio: do not toggle_index in open_project

When opening a new project `m_prject_tree_view->toggle_index()` is not
needed because `m_project_tree_view->set_model()` already updates the
indexes.

Userland/DevTools/HackStudio/HackStudioWidget.cpp

@@ -190,7 +190,6 @@ void HackStudioWidget::open_project(const String& root_path)
     ASSERT(m_project);
     if (m_project_tree_view) {
         m_project_tree_view->set_model(m_project->model());
-        m_project_tree_view->toggle_index(m_project_tree_view->model()->index(0, 0));
         m_project_tree_view->update();
     }
     if (Debugger::is_initialized()) {