Access root->simple_rte_array instead of Query->rtable for 2 more cases.

When I am understanding the relationship between Query->rtable and
root->simple_rte_array, I'd like to assume that Query->rtable should be
never used
when root->simple_rte_array is ready. I mainly checked two places,
make_one_rel and
create_plan with the below hacks.

{
List *l = root->parse->rtable;
root->parse->rtable = NIL;
make_one_rel.. or create_plan_recurse..
root->parse->rtable = l;
}

Then I found adjust_appendrel_attrs_mutator and infer_arbiter_indexes still
use it. The attached patch fixed it by replacing the rt_fetch with
planner_rt_fetch,
all the tests passed.

--
Best Regards
Andy Fan (https://www.aliyun.com/)