BUG #18290: \di+ can not show the same name indexes

The following bug has been logged on the website:

Bug reference:      18290
Logged by:          Yongtao Huang
Email address:      yongtaoh2022@gmail.com
PostgreSQL version: 16.1
Operating system:   centos7
Description:

``` SQL
gpadmin@gpadmin-host:~$ psql
psql (16.1)
Type "help" for help.

gpadmin=# create table t1(c1 int);
CREATE TABLE
gpadmin=# create temp table t2(c1 int);
CREATE TABLE
gpadmin=#
gpadmin=# create index idx1 on t1(c1);
CREATE INDEX
gpadmin=# create index idx1 on t2(c1);
CREATE INDEX

gpadmin=# \d+ t1
                                           Table "public.t1"
 Column |  Type   | Collation | Nullable | Default | Storage | Compression |
Stats target | Description
--------+---------+-----------+----------+---------+---------+-------------+--------------+-------------
 c1     | integer |           |          |         | plain   |             |
             |
Indexes:
    "idx1" btree (c1)
Access method: heap

gpadmin=# \d+ t2
                                          Table "pg_temp_3.t2"
 Column |  Type   | Collation | Nullable | Default | Storage | Compression |
Stats target | Description
--------+---------+-----------+----------+---------+---------+-------------+--------------+-------------
 c1     | integer |           |          |         | plain   |             |
             |
Indexes:
    "idx1" btree (c1)
Access method: heap

gpadmin=# \di+
                                          List of relations
  Schema   | Name | Type  |  Owner  | Table | Persistence | Access method |
  Size    | Description
-----------+------+-------+---------+-------+-------------+---------------+------------+-------------
 pg_temp_3 | idx1 | index | gpadmin | t2    | temporary   | btree         |
8192 bytes |
(1 row)

```
Both table `t1` and temp table `t2` have index idx, but `\di` only shows the
index of table `t2`.

Related link: https://github.com/greenplum-db/gpdb/issues/15791

Bug catcher: Hao Zhang <hao-hz.zhang@broadcom.com> and Yongtao Huang
<yongtaoh2022@gmail.com>