Expecting group::certify but it's group:certify

Background: !708 (comment 453796248)

We renamed the group::certify label to the non-scoped ~"group:certify" label so we can keep track of Certify issues without pulling off the groupproduct planning label.

I saw a case where this was an issue: gitlab-org/gitlab#295640 (comment 474275495)

This may not be critical but still an issue so I created this.

/cc @gl-quality/eng-prod