Not sure I totally understand the question but ....
If you had to restore a SQL dump to recover from a borked upgrade to a new DB - makes no difference if the server is remote or local, then one needs to change the config.php file of the moodle - DB lines.
And the backup of the code directory would also have to be restored - code version matches DB version.
After checking that the site functions without errors, one could remove the old DB from the server ... remote or local. To be safe, one could do a sql dump of that DB and archive that dump. And also remove the borked code directory to avoid confusion later.
Again checking/changing the config.php file to point to the restored DB on remote server or local.
Or am I not understanding?
Why did we create a new PG cluster to begin with? Was it felt that a new cluster would protect what they had should something concerning moodle hickup? Dunno what that would be if config was pointed to a specific DB.
'SoS', Ken