This reverts commit 6823e7de.

Originally implemented in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21839, but an
error was reported in
https://gitlab.com/gitlab-org/gitlab-ce/issues/51729 resulting in a
workaround introduced in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21879.

Now Rails 5.2 is used, this workaround no longer seems needed, so this
reverts it.