Editing GitLab V18 Upgrade (section)

==Why it happens:==

* **Security hardening:** Newer PostgreSQL versions or stricter configurations of GitLab's chart might restrict access to sensitive functions like `pg_ls_waldir()` to only superusers or specific roles (like `pg_monitor`).
* **Non-superuser GitLab user:** GitLab typically runs with a non-superuser database user for security reasons. This user might not have the permissions by default.
* **Monitoring tools:** Sometimes, this error isn't from GitLab's core migrations but from a monitoring tool (like `postgres_exporter` for Prometheus) trying to gather WAL-related metrics. If the GitLab upgrade involves an upgrade of the bundled PostgreSQL or a change in how permissions are managed, this can manifest.