Issue #3426229: Gitlab CI testing of core version of the module does not fail on deprecations

.gitlab-ci.yml

@@ -66,6 +66,8 @@ variables:
   CI_DEBUG_SERVICES: "true"
   _TARGET_DB_TYPE: "mariadb"
   _TARGET_DB_VERSION: "10.6"
+  # Always show environment variables, to help in debugging CI problems.
+  _SHOW_ENVIRONMENT_VARIABLES: '1'
 
 
 ###################################################################################
@@ -232,6 +234,7 @@ phpunit (next major):
     - when: on_success
   variables:
     _PHPUNIT_EXTRA: '--types PHPUnit-$TEST_TYPE --module $MODULE'
+    SYMFONY_DEPRECATIONS_HELPER: 'ignoreFile=$CI_PROJECT_DIR/$_WEB_ROOT/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