Adding loose foreign keys ci_group_variables,ci_minutes_additional_packs

These [loose foreign
keys](https://docs.gitlab.com/ee/development/database/loose_foreign_keys.html)
are the first step to removing the cross-database foreign keys between
`main` and `ci` databases.

These 2 foreign keys have been determined to be safe for swapping to
loose foreign keys per
https://gitlab.com/gitlab-org/gitlab/-/issues/348269 .

lib/gitlab/database/gitlab_loose_foreign_keys.yml

@@ -67,3 +67,11 @@ project_pages_metadata:
   - table: ci_job_artifacts
     column: artifacts_archive_id
     on_delete: async_nullify
+ci_group_variables:
+  - table: namespaces
+    column: group_id
+    on_delete: async_delete
+ci_minutes_additional_packs:
+  - table: namespaces
+    column: namespace_id
+    on_delete: async_delete