### Godot version

4.0beta17

### System information

Linux Mint 21.1

### Issue description

When editing animations for the **frame** property of **Sprite2D**, the preview image does not respect the **region_rect** specified in the Sprite2D's properties.

Godot 4.0 (tested with alpha1 to beta17)
![Screenshot from 2023-02-05 21-19-29](https://user-images.githubusercontent.com/2348534/216868394-45a9dc42-ce4b-4b11-82cb-4491aea46d9b.png)

Godot 3.5
![Screenshot from 2023-02-05 21-19-43](https://user-images.githubusercontent.com/2348534/216868543-cff6eb60-a431-4138-8fa6-5c30a54de0e1.png)

As can be seen in the second screenshot, the region rect is applied to the key preview image in Godot 3.5, but is ignored in Godot 4.0.


### Steps to reproduce

Steps:

1. Set a region rect on a Sprite2D node
2. Add Sprite2D.frame as a track to an AnimationPlayer
3. Insert key
4. Key preview does not take region rect into account

### Minimal reproduction project

[MRP.zip](https://github.com/godotengine/godot/files/10637055/MRP.zip)

if (len == 0) {
			len = preview_len;
		}
		int pixel_len = len * p_pixels_sec;
		int pixel_begin = p_x;
		int pixel_end = p_x + pixel_len;
		if (pixel_end < p_clip_left) {
			return;
		}
		if (pixel_begin > p_clip_right) {
			return;
		}
		int from_x = MAX(pixel_begin, p_clip_left);
		int to_x = MIN(pixel_end, p_clip_right);
		if (get_animation()->track_get_key_count(get_track()) > p_index + 1) {
			float limit = MIN(len, get_animation()->track_get_key_time(get_track(), p_index + 1) - get_animation()->track_get_key_time(get_track(), p_index));
			int limit_x = pixel_begin + limit * p_pixels_sec;
			to_x = MIN(limit_x, to_x);
		}
		if (to_x <= from_x) {
			return;
		}
		Ref<Font> font = get_theme_font(SNAME("font"), SNAME("Label"));
		int font_size = get_theme_font_size(SNAME("font_size"), SNAME("Label"));
		float fh = int(font->get_height(font_size) * 1.5);
		Rect2 rect = Rect2(from_x, (get_size().height - fh) / 2, to_x - from_x, fh);
		draw_rect(rect, Color(0.25, 0.25, 0.25));
		Vector<Vector2> lines;
		lines.resize((to_x - from_x + 1) * 2);
		preview_len = preview->get_length();