Use config override instead of event subscirber to enable the profile split

I tested this one with D10 and profile_split_enable 2.0.1. Without this change, the profile enable split does not work at all. Thank you!

This MR adds tests, and GitLab automated tests aren't configured for this project. Locally, they pass, but only after I install the config_split module:

$ ../vendor/phpunit/phpunit/phpunit -c core/ modules/contrib/profile_split_enable/ --verbose
PHPUnit 9.6.15 by Sebastian Bergmann and contributors.

Runtime:       PHP 8.1.16
Configuration: /var/www/html/web/core/phpunit.xml.dist

Testing /var/www/html/web/modules/contrib/profile_split_enable
....                                                                4 / 4 (100%)

Time: 00:05.004, Memory: 4.00 MB

OK (4 tests, 5 assertions)

Without config_split:

$ ../vendor/phpunit/phpunit/phpunit -c core/ modules/contrib/profile_split_enable/ --verbose
PHP Fatal error:  Trait "Drupal\Tests\config_split\Kernel\SplitTestTrait" not found in /var/www/html/web/modules/contrib/profile_split_enable/tests/src/Kernel/Config/StatusOverrideTest.php on line 9

Fatal error: Trait "Drupal\Tests\config_split\Kernel\SplitTestTrait" not found in /var/www/html/web/modules/contrib/profile_split_enable/tests/src/Kernel/Config/StatusOverrideTest.php on line 9

Is config_split just a missing dev dependency or is a hard dependency for this module?

Based on this module's README, it appears that config_split is optional:

When using config_split it allows you to dynamically enable and import
configuration from a config split for each of your custom installation
profiles.

I just added config_split as a test dependency to the merge request.

I came across this issue, and the changes here (mostly) resolved the issue I was having (drush not being able to import profile-based splits)

The issue is mostly resolved because the referenced branch here is behind 2.x (https://git.drupalcode.org/project/profile_split_enable/-/compare/326217...). I created a patch locally to merge these changes, but was unable to get the test_dependencies change to apply cleanly. When I removed that change the patch applied and my issue was resolved.

If the changes in this ticket incorporate the latest changes from 2.x and the test_dependencies change is able to apply cleanly my vote is to get this merged. I am leaving this ticket as needs review since there is no patch that applies cleanly, but from a "the change fixes the issue" standpoint I would say this is RTBC.

Yes, unfortunately modules doesn't work as expected using drush.

The fix from MR as a patch for branch 2.x is attached.