Identify issues without a team label

All issues should really have a team label to improve their discovery.

There are some common scenarios where this is forgotten:

1. Bugs raised
2. gitlab-org/gitlab-ce3412464 and gitlab-org/gitlab-ce2492649 issues
3. gitlab-org/gitlab-ce3011727 and gitlab-org/gitlab-ce3011693 issues
4. old issue from before this was a pattern

Issues without a known team label should be highlighted and improved

Number 4. is very problematic as these issues are really difficult to find. Possibly even more so than unlabelled issues if they have an uncommonly used feature label. Adding team labels to these types of issues would make them discoverable again

Questions

Who to ping? Because it's not possible to easily determine the team as we have no way of mapping an individual feature label back to a team label