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>