Self-hosted: `pg-wal` files grow indefinitely because `analytics` replication falls behind (see #40546)

# Bug report - [X] I confirm this is a bug with Supabase, not with my own application. - [X] I confirm I have searched the [Docs](https://docs.supabase.com), GitHub [Discussions](https://github.com/supabase/supabase/discussions), and [Discord](https://discord.supabase.com). ## Describe the bug Even an idle self-hosted supabase instance may suffer from indefinitely growing `pg_wal` files because the `analytics` replication slot falls indefinitely behind. I saw that in a self-hosted instance on fly.io and found #40546 describing the same problem. ## To Reproduce I created a reproducer, see: https://github.com/tvogel/supabase/blob/reproducer-40546/docker/PROBLEM.md ## Expected behavior In an idle scenario, the `pg_wal` directory should fluctuate around the `min_wal_size`. ## System information - OS: openSUSE Tumbleweed 20260226 ## Additional context I am not sure, this only happens when WAL archiving is on. I do use WAL-G backups on the fly.io instance and also configured fake WAL backups for the reproducer.