Issue analytics: support filtering for undefined categories

Problem to solve

When looking at an Issue related Insights report, I would like to understand which issues are Undefined.

Insights	Issue analytics (using IS NOT filtering)

Proposal

With the recently drill down functionality added that was added to insights reports (Insights: Drill down from charts (#372215 - closed)), users can click into an individual priority to see a filtered list of issues on the Issue analytics page.

I would be helpful to also be able to do the same for Undefined issues.

Questions

Can this accomplished in all cases by using the IS NOT filters? For example:

https://gitlab.com/gitlab-org/gitlab/-/analytics/issues_analytics?scope=all&not[label_name][]=priority%3A%3A1&not[label_name][]=priority%3A%3A2&not[label_name][]=priority%3A%3A3&not[label_name][]=priority%3A%3A4&search=labl+lable

OR, would the proposal mentioned in Allow to set a custom label for the "undefined"... (#14753) make more sense?

Intended users

• Parker (Product Manager)
• Delaney (Development Team Lead)
• Presley (Product Designer)
• Sasha (Software Developer)

Feature Usage Metrics

Does this feature require an audit event?

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