### Godot version

master

### System information

Ubuntu

### Issue description

I think one of the recent changes wrapped the project converter in `#ifndef DISABLE_DEPRECATED` but missed the coresponding code in `main.cpp` (and potentially other places).
```
main/main.cpp: In static member function 'static bool Main::start()':
main/main.cpp:2551:33: error: 'ProjectConverter3To4' was not declared in this scope
 2551 |                 int exit_code = ProjectConverter3To4(converter_max_kb_file, converter_max_line_length).convert();
      |                                 ^~~~~~~~~~~~~~~~~~~~
main/main.cpp:2556:33: error: 'ProjectConverter3To4' was not declared in this scope
 2556 |                 int exit_code = ProjectConverter3To4(converter_max_kb_file, converter_max_line_length).validate_conversion();
```

### Steps to reproduce

for instance, try to compile with `deprecated = "no"` in your `custom.py`.

### Minimal reproduction project

n/a
audio_driver = GLOBAL_GET("audio/driver/driver");
	}
	
	DEV_ASSERT(NULL_AUDIO_DRIVER == AudioDriverManager::get_driver(AudioDriverManager::get_driver_count() - 1)->get_name());
	for (int i = 0; i < AudioDriverManager::get_driver_count(); i++) {
		if (audio_driver == AudioDriverManager::get_driver(i)->get_name()) {
			audio_driver_idx = i;
			break;
		}
	}
	if (audio_driver_idx < 0) {
		
		
		audio_driver_idx = 0;
	}
	if (Engine::get_singleton()->get_write_movie_path() != String()) {
		
		audio_driver_idx = AudioDriverManager::get_driver_count() - 1;
		AudioDriverDummy::get_dummy_singleton()->set_use_threads(false);
	}
	{
		window_orientation = DisplayServer::ScreenOrientation(int(GLOBAL_DEF_BASIC("display/window/handheld/orientation", DisplayServer::ScreenOrientation::SCREEN_LANDSCAPE)));
	}
	{
		window_vsync_mode = DisplayServer::VSyncMode(int(GLOBAL_DEF("display/window/vsync/vsync_mode", DisplayServer::VSyncMode::VSYNC_ENABLED)));
		if (disable_vsync) {
			window_vsync_mode = DisplayServer::VSyncMode::VSYNC_DISABLED;
		}
	}
	Engine::get_singleton()->set_physics_ticks_per_second(GLOBAL_DEF_BASIC(PropertyInfo(Variant::INT, "physics/common/physics_ticks_per_second", PROPERTY_HINT_RANGE, "1,1000,1"), 60));