chore(tech-debt): Finalize gui_2.py cleanup and test suite discipline

tests/test_gui_phase3.py

@@ -13,15 +13,6 @@ sys.modules['imgui_bundle.hello_imgui'] = MagicMock()
 
 from gui_2 import App
 
-@pytest.fixture
-def app_instance():
- with patch('gui_2.load_config', return_value={}):
-  with patch('gui_2.project_manager.load_project', return_value={}):
-   with patch('gui_2.session_logger.open_session'):
-    app = App()
-    app.ui_files_base_dir = "."
-    return app
-
 def test_track_proposal_editing(app_instance):
  # Setup some proposed tracks
  app_instance.proposed_tracks = [