`StatusPage::PublishedIncident#track` used `safe_find_or_create_by` to
circumvent a potential race condition in case of a duplicate published
issue.  This, however, uses subtransactions under the hood which is
problematic in nested transactions.

See https://gitlab.com/groups/gitlab-org/-/epics/6540 for more context.

In the rare event of `ActiveRecord::RecordNotUnique` users end up seeing
a meaningful error message. This behaviour is acceptable and that's why
switched to unsafe method `find_or_create_by`.