Migrations specs are still run in unit test jobs
This can be seen in #387084271:
1617 KNAPSACK_TEST_FILE_PATTERN: spec/{bin,config,db,dependencies,factories,finders,frontend,graphql,haml_lint,helpers,initializers,javascripts,lib,models,policies,presenters,rack_servers,routing,rubocop,serializers,services,sidekiq,tasks,uploaders,validators,views,workers,elastic_integration}{,/**/}*_spec.rb
1618 Checking gitaly-ruby Gemfile...
1619 Checking gitaly-ruby bundle...
1620 Warning: the running version of Bundler (1.17.2) is older than the version that created the lockfile (1.17.3). We suggest you upgrade to the latest version of Bundler by running `gem install bundler`.
1621 The Gemfile's dependencies are satisfied
1622 Trying to connect to gitaly: ..... OK
1623 Report specs:
1624 spec/models/ci/build_spec.rb
1625 spec/models/merge_request_diff_spec.rb
1626 spec/services/projects/overwrite_project_service_spec.rb
1627 spec/lib/banzai/filter/milestone_reference_filter_spec.rb
1628 spec/lib/gitlab/middleware/go_spec.rb
1629 spec/services/projects/fork_service_spec.rb
1630 spec/serializers/pipeline_serializer_spec.rb
1631 spec/tasks/gitlab/check_rake_spec.rb
1632 spec/services/projects/lfs_pointers/lfs_download_service_spec.rb
1633 spec/services/auto_merge/base_service_spec.rb
1634 spec/models/gpg_key_subkey_spec.rb
1635 spec/serializers/group_child_entity_spec.rb
1636 spec/workers/post_receive_spec.rb
1637 spec/models/concerns/avatarable_spec.rb
1638 spec/services/todos/destroy/private_features_service_spec.rb
1639 spec/models/project_services/teamcity_service_spec.rb
1640 spec/services/todos/destroy/group_private_service_spec.rb
1641 spec/presenters/ci/build_presenter_spec.rb
1642 spec/models/protected_branch_spec.rb
1643 spec/services/clusters/gcp/provision_service_spec.rb
1644 spec/lib/gitlab/background_migration/migrate_legacy_artifacts_spec.rb
1645 spec/models/trending_project_spec.rb
1646 spec/workers/remove_expired_members_worker_spec.rb
1647 spec/lib/gitlab/background_migration/remove_restricted_todos_spec.rb
1648 spec/models/merge_request/pipelines_spec.rb
1649 spec/lib/gitlab/import_export/relation_factory_spec.rb
1650 spec/services/notes/build_service_spec.rb
1651 spec/models/route_spec.rb
1652 spec/lib/gitlab/metrics/dashboard/finder_spec.rb
1653 spec/services/verify_pages_domain_service_spec.rb