### Godot version

v4.2.rc.mono.custom_build [ad72de508]

### System information

Windows 10

### Issue description

As I pointed out several times earlier in [#80284](https://github.com/godotengine/godot/pull/80284#issuecomment-1722120503), the references to singletons in `GDScript` are still not updated after the `GDExtension` reload.

https://github.com/godotengine/godot/assets/7782218/f90052a5-0de2-4310-8235-f0b9e2f74b3a

Singletons themselves are updated and work correctly, but references to these singletons are not updated in `@tool` scripts. That is, `Engine.get_singleton` returns the actual working reference, but using the singleton directly through its name causes errors.

### Steps to reproduce

* Clone `4.2.reload_singleton` branch from the MRP repository https://github.com/DmitriySalnikov/gde_test_cases/tree/4.2.reload_singleton
* Build as usual
* Open the project from the `project/` folder
* Add one character to the source code and rebuild
* Focus on the editor to reload extension
* Watch for error spam when calling by singleton name

### Minimal reproduction project

https://github.com/DmitriySalnikov/gde_test_cases/tree/4.2.reload_singleton
}
	}
#ifdef TOOLS_ENABLED
	
	
	GDScriptDocGen::generate_docs(this, parser.get_tree());
#endif
#ifdef DEBUG_ENABLED
	for (const GDScriptWarning &warning : parser.get_warnings()) {
		if (EngineDebugger::is_active()) {
			Vector<ScriptLanguage::StackInfo> si;
			EngineDebugger::get_script_debugger()->send_error("", get_script_path(), warning.start_line, warning.get_name(), warning.get_message(), false, ERR_HANDLER_WARNING, si);
		}
	}
#endif
	if (can_run) {
		err = _static_init();
		if (err) {
			return err;
		}
	}
#ifdef TOOLS_ENABLED
	if (can_run && p_keep_state) {
		_restore_old_static_data();
	}
#endif
	reloading = false;
	return OK;
}
ScriptLanguage *GDScript::get_language() const {