`win_execute` should(?) update popup properties (`scrollbar`) about vim

[habamax]

Adding popup_adjust_position() to f_popup_getpos fixes it, though not sure if this is correct approach.

    void
f_popup_getpos(typval_T *argvars, typval_T *rettv)
{
    dict_T	*dict;
    int		id;
    win_T	*wp;
    int		top_extra;
    int		left_extra;

    if (rettv_dict_alloc(rettv) == FAIL)
	return;

    if (in_vim9script() && check_for_number_arg(argvars, 0) == FAIL)
	return;

    id = (int)tv_get_number(argvars);
    wp = find_popup_win(id);
    if (wp == NULL)
	return;  // invalid {id}
   
    popup_adjust_position(wp);
    ...