### 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.
if (!editable) {
		return;
	}
	if (in_action) {
		pending_action_end = true;
	}
	_push_current_op();
	if (undo_stack_pos == nullptr) {
		return; 
	}
	deselect();
	TextOperation op = undo_stack_pos->get();
	_do_text_op(op, false);
	current_op.version = op.version;
	if (undo_stack_pos->get().chain_forward) {
		while (true) {
			ERR_BREAK(!undo_stack_pos->next());