### 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
} else {
				project_path = path;
			}
#ifdef TOOLS_ENABLED
			editor = true;
#endif
		} else if (I->get() == "-b" || I->get() == "--breakpoints") { 
			if (I->next()) {
				String bplist = I->next()->get();
				breakpoints = bplist.split(",");
				N = I->next()->next();
			} else {
				OS::get_singleton()->print("Missing list of breakpoints, aborting.\n");
				goto error;
			}
		} else if (I->get() == "--frame-delay") { 
			if (I->next()) {
				frame_delay = I->next()->get().to_int();
				N = I->next()->next();
			} else {
				OS::get_singleton()->print("Missing frame delay argument, aborting.\n");
				goto error;
			}
		} else if (I->get() == "--time-scale") { 
			if (I->next()) {
				Engine::get_singleton()->set_time_scale(I->next()->get().to_float());
				N = I->next()->next();
			} else {
				OS::get_singleton()->print("Missing time scale argument, aborting.\n");
				goto error;