Updater function reports issue with data directory—should mention update directory

[Helianthropy]

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Steps to reproduce

1. Install older version of Nextcloud
2. Configure config.php file with datadirectory
3. Configure updatedirectory as '' (empty)
4. Attempt update (web or command line)

Expected behaviour

Update progresses with understandable error messages.

Actual behaviour

Update fails with incorrect error (Error message: Could not read updater or data directory from config.php.)

Server configuration

Web server: Nginx

Database: Maria

PHP version: 8.3

Nextcloud version: 31.0.12