Add tech debt tracking for CI group

Related to gitlab-org/verify-stage#15 (closed)

Why is this change being made?

We found that using P* labels to score our technical debt issues can be challenging. Given that we have a board for tracking tech debt items I've added guidelines on how we track and score the impact of technical debt issues.

I've compiled a list of factors that can determine what ~P* label to assign to a technical debt issue.