### 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
continue; 
				}
				display_server = DisplayServer::create(i, rendering_driver, window_mode, window_vsync_mode, window_flags, window_position, window_size, init_screen, err);
				if (err == OK && display_server != nullptr) {
					break;
				}
			}
		}
		if (err != OK || display_server == nullptr) {
			ERR_PRINT("Unable to create DisplayServer, all display drivers failed.");
			return err;
		}
	}
	if (display_server->has_feature(DisplayServer::FEATURE_ORIENTATION)) {
		display_server->screen_set_orientation(window_orientation);
	}
	if (GLOBAL_GET("debug/settings/stdout/print_fps") || print_fps) {
		
		switch (window_vsync_mode) {
			case DisplayServer::VSyncMode::VSYNC_DISABLED:
				print_line("Requested V-Sync mode: Disabled");
				break;
			case DisplayServer::VSyncMode::VSYNC_ENABLED:
				print_line("Requested V-Sync mode: Enabled - FPS will likely be capped to the monitor refresh rate.");
				break;
			case DisplayServer::VSyncMode::VSYNC_ADAPTIVE:
				print_line("Requested V-Sync mode: Adaptive");
				break;
			case DisplayServer::VSyncMode::VSYNC_MAILBOX:
				print_line("Requested V-Sync mode: Mailbox");