Issue #3426229 test conversion with weak deprecations

Closes #3426229

.gitlab-ci.yml

@@ -137,8 +137,6 @@ composer:
     - cp -R /tmp/drupal-core/composer .
     # Copy to web as well as \Drupal\Composer\Composer will expect it be there.
     - cp -R /tmp/drupal-core/composer web
-    # Ignore the same deprecations as core.
-    - cp -R /tmp/drupal-core/core/.deprecation-ignore.txt web/core
 
 composer (previous minor):
   before_script:
@@ -236,6 +234,7 @@ phpunit (next major):
     - when: on_success
   variables:
     _PHPUNIT_EXTRA: '--types PHPUnit-$TEST_TYPE --module $MODULE'
+    SYMFONY_DEPRECATIONS_HELPER: 'ignoreFile=core/.deprecation-ignore.txt'
   # This is a really dirty hack to work around a possible bug in Drush when it runs against
   # Drupal core 11.x-dev:
   # https://git.drupalcode.org/project/automatic_updates/-/jobs/723857#L209