Class "\Drupal\config_pages\Commands\Drush\ConfigPagesCommands" does not exist

Problem/Motivation

The updates made to add Drush 12 support broke support for Drush 11, due to a missed update to the `drush.services.yml` file. When pulling the latest 2.x version of the module and running a drush command like `drush updb` results in the following fatal error:

`Class "\Drupal\config_pages\Commands\Drush\ConfigPagesCommands" does not exist `

This is due to the work done in issue #3417917, where the directory structure to the ConfigPagesCommand was changed to align with Drush 12 requirements, but the path was not updated in the `drush.services.yml` file that is used by Drush 11.

Steps to reproduce

1. Install the module in an environment running Drush 11.
2. Run a drush command.
3. Error about missing class file.

Proposed resolution

Update the `drush.services.yml` file to point to the updated path to the command class.