### Godot version

4.1.dev (dc625bcbfc5b587ba8867481ee7a1f6a567c25d0)

### System information

Mageia 9, Linux

### Issue description

When importing a project in current `master`, the following error is raised for each asset that gets imported:
```
Attempting to parent and popup a dialog that already has a parent.
```

It seems to be raised once per asset, caused by the progress dialog.

CC @bruvzg

### Steps to reproduce

- Import a new project in Godot that contains importable assets, e.g. https://github.com/RPicster/godot4-demo-desert-light

### Minimal reproduction project

See above.
#ifndef PROGRESS_DIALOG_H
#define PROGRESS_DIALOG_H
#include "scene/gui/box_container.h"
#include "scene/gui/button.h"
#include "scene/gui/label.h"
#include "scene/gui/popup.h"
#include "scene/gui/progress_bar.h"
class BackgroundProgress : public HBoxContainer {
	GDCLASS(BackgroundProgress, HBoxContainer);
	_THREAD_SAFE_CLASS_
	struct Task {
		HBoxContainer *hb = nullptr;
		ProgressBar *progress = nullptr;
	};
	HashMap<String, Task> tasks;
	HashMap<String, int> updates;
	void _update();
protected:
	void _add_task(const String &p_task, const String &p_label, int p_steps);
	void _task_step(const String &p_task, int p_step = -1);
	void _end_task(const String &p_task);
	static void _bind_methods();
public:
	void add_task(const String &p_task, const String &p_label, int p_steps);
	void task_step(const String &p_task, int p_step = -1);
	void end_task(const String &p_task);
	BackgroundProgress() {}
};
class ProgressDialog : public PopupPanel {