### Godot version

4.0 beta 15

### System information

Windows 10

### Issue description

It happened with both Google IME and MS-IME, and there was no problem until Beta14.
When typing Japanese characters, it is common to select a character from the suggestion window and then start typing the next character before confirming.
In this case, uncommitted characters are forcibly committed, and input of the next character begins.

**↓Beta15**

https://user-images.githubusercontent.com/186786/214753450-b493cca6-2644-4b3d-8cd2-660565cc3547.mp4

**↓Beta14**

https://user-images.githubusercontent.com/186786/214755127-dde819cc-4d63-403a-99b0-09821671f74e.mp4



### Steps to reproduce

It happened with both Google IME and MS-IME in beta15

### Minimal reproduction project

It is project independent and happens in the editor.
Vector<Vector2> sel = TS->shaped_text_get_selection(text_rid, caret_column, caret_column + ime_text.length());
						for (int i = 0; i < sel.size(); i++) {
							Rect2 rect = Rect2(sel[i].x + ofs.x, ofs.y, sel[i].y - sel[i].x, text_height);
							if (rect.position.x + rect.size.x <= x_ofs || rect.position.x > ofs_max) {
								continue;
							}
							if (rect.position.x < x_ofs) {
								rect.size.x -= (x_ofs - rect.position.x);
								rect.position.x = x_ofs;
							} else if (rect.position.x + rect.size.x > ofs_max) {
								rect.size.x = ofs_max - rect.position.x;
							}
							rect.size.y = caret_width;
							RenderingServer::get_singleton()->canvas_item_add_rect(ci, rect, caret_color);
						}
					}
					{
						
						if (ime_selection.y > 0) {
							Vector<Vector2> sel = TS->shaped_text_get_selection(text_rid, caret_column + ime_selection.x, caret_column + ime_selection.x + ime_selection.y);
							for (int i = 0; i < sel.size(); i++) {
								Rect2 rect = Rect2(sel[i].x + ofs.x, ofs.y, sel[i].y - sel[i].x, text_height);
								if (rect.position.x + rect.size.x <= x_ofs || rect.position.x > ofs_max) {
									continue;
								}
								if (rect.position.x < x_ofs) {
									rect.size.x -= (x_ofs - rect.position.x);
									rect.position.x = x_ofs;
								} else if (rect.position.x + rect.size.x > ofs_max) {