DrupalCon Seattle 2019 major issue triage

Problem/Motivation

See the parent issue 🌱 [meta] Major issue triage Active for information on major issue triage.

Much issue triage results in non-creditable issue states (like cannot reproduce, duplicate, etc.), but it is time-consuming work. Therefore, we typically track triage credit with stub issues. However, these stub issues were never created for major triage at events.

Proposed resolution

Add stub issues for major triage events, and retroactively add credits where possible.