Use replaceWith, not replace, in #ajax form settings

I've created a merge request with the adjustment.

I reviewed the MR, and it does just what the change record says. (Thanks for adding a link to the change record in the issue summary.) I also searched for other uses of 'method' => 'replace',, and I did not find any.

The hard part is testing. From the issue description:

Both methods work identically before Drupal 10.3.0, but starting in this version, only replaceWith is supported.

Not quite. Starting with Drupal 10.3.0, replace generates a deprecation notice, which is not easy to test. I did it by hacking the line

        @trigger_error('Using "replace" as the method in #ajax property is deprecated in drupal:10.3.0 and is removed from drupal:11.0.0. Use "replaceWith" instead. See https://www.drupal.org/project/drupal/issues/3303557', E_USER_DEPRECATED);

in Drupal\Core\Render\Element\RenderElementBase::preRenderAjaxForm(), removing the @ so that the error is not suppressed. After that change, I see a deprecation notice (debug level) in the logs each time I load the page at /admin/config/system/shield.

When I make the change in the MR, I do not see any log messages when loading that page.