### 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.
_create_undo_state();
	if (undo_stack_pos == nullptr) {
		return;
	}
	undo_stack_pos = undo_stack_pos->next();
	while (undo_stack_pos) {
		List<TextOperation>::Element *elem = undo_stack_pos;
		undo_stack_pos = undo_stack_pos->next();
		undo_stack.erase(elem);
	}
	_create_undo_state();
}
void LineEdit::_clear_undo_stack() {
	undo_stack.clear();
	undo_stack_pos = nullptr;
	_create_undo_state();
}
void LineEdit::_create_undo_state() {
	TextOperation op;
	op.text = text;
	op.caret_column = caret_column;
	op.scroll_offset = scroll_offset;
	undo_stack.push_back(op);
}
Key LineEdit::_get_menu_action_accelerator(const String &p_action) {