Refactor InstallerNonDefaultDatabaseDriverTest to avoid asserting content of settings.php

Problem/Motivation

Noted in ✨ Introduce database driver extensions and autoload database drivers' dependencies Fixed , https://git.drupalcode.org/project/drupal/-/merge_requests/3169#note_182014.

The InstallerNonDefaultDatabaseDriverTest asserts on actual strings of the settings.php file, which is brittle.

Steps to reproduce

Proposed resolution

Refactor to assert on arrays instead (from connection info?)

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet