Follow-up: remove ignore rule for ProjectAutoDevops#domain

Once https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28460 & https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28574 are been deployed, remove the ignore rule in a new release.

[1] https://docs.gitlab.com/ee/development/what_requires_downtime.html#step-2-removing-the-ignore-rule