Dead GUC enable_geqo in CBDB, but not in Postgres

### Cloudberry Database version

main

### What happened

Commit 9e6035c5fefcbcd94be16b28935e91ba7c4bc339 bring back enable_geqo, but the GUC is still not used in CBDB:
https://github.com/search?q=repo%3Acloudberrydb%2Fcloudberrydb+enable_geqo&type=code

In Postgres, it surely be used in planner:
https://github.com/search?q=repo%3Apostgres%2Fpostgres%20enable_geqo&type=code

Though it's put in codes, but still a dead GUC in codes and users can not set it when using CBDB.
Why GPDB/CBDB doesn't use enable_geqo unlike Postgres, shall we use it in codes or remove it entirely if there is any consideration by GPDB?

### What you think should happen instead

_No response_

### How to reproduce

NULL

### Operating System

All

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes, I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://cloudberrydb.org/community/coc).

Start with the repository search for enable_geqo and compare its CBDB occurrences with the PostgreSQL planner references linked in the issue. Review commit 9e6035c5fefcbcd94be16b28935e91ba7c4bc339 and determine whether the GUC should be connected to planner behavior or removed; the issue provides no named files or tests.

Written by the indexing model from the issue text.