Issue #3421641 use mariadb-10.6

Closes #3421641

.gitlab-ci.yml

@@ -32,8 +32,9 @@ include:
   # As long as you include this, any future includes added by the Drupal Association will be accessible to your pipelines automatically.
   # View these include files at https://git.drupalcode.org/project/gitlab_templates/
   ################
-  - project: $_GITLAB_TEMPLATES_REPO
-    ref: $_GITLAB_TEMPLATES_REF
+  # @todo Remove when https://www.drupal.org/i/3421674 is fixed.
+  - project: "issue/gitlab_templates-3421674"
+    ref: "3421674-add-mariadb-simpletest-db"
     file:
       - '/includes/include.drupalci.main.yml'
       # EXPERIMENTAL: For Drupal 7, remove the above line and uncomment the below.
@@ -56,6 +57,8 @@ variables:
 #   SKIP_ESLINT: '1'
   # @todo Remove this line when https://drupal.org/i/3414093 is fixed.
   CI_DEBUG_SERVICES: "true"
+  _TARGET_DB_TYPE: "mariadb"
+  _TARGET_DB_VERSION: "10.6"
 
 
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