Supabase Cron doesn't work with custom DB name when self-hosting

# Bug report <!-- ⚠️ We receive a lot of bug reports which have already been solved or discussed. If you are looking for help, please try these first: - Docs: https://docs.supabase.com - Discussions: https://github.com/supabase/supabase/discussions - Discord: https://discord.supabase.com Before opening a bug report, please verify the following: --> - [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 It's not currently possible to use pg_cron when POSTGRES_DB is set to any value except the default "postgres". When you try activating the extension, it says that cron.database_name has to be set. ## To Reproduce Steps to reproduce the behavior, please provide code snippets or a repository: 1. Set up the default Supabase deployment with docker compose. 2. Go to the integrations tab and then Cron. 3. Click to enable the extension. 4. See error about wrong database name. ## Expected behavior The default postgresql.conf file specified in the db container includes the hard-coded line `cron.database_name = postgres`. This should instead use the value set in POSTGRES_DB.