gitlab in the db:migrate-from-v11.11.0 CI job

This CI job still uses git fetch https://gitlab.com/gitlab-org/gitlab-ee.git v11.11.0-ee . We should change this to git fetch https://gitlab.com/gitlab-org/gitlab.git v11.11.0-ee. We still need the EE tag, as this tag is a version prior to the single codebase.