Some of our targets, namely engine builds that are used to build and deploy artifacts, are built as part of the merge queue.

What that means, in practice, is they will never show up on https://flutter-dashboard.appspot.com/, because they are (functionally) not part of the post-submit process. IMO it would be less confusing if they did show up, even if they always immediately showed up as successful. One way we could do this is write tasks optimistically during the merge queue process is to Firestore.

This is useful for a number of reasons:

• Seeing how long builds took
• Seeing if builds required any reruns or were flaky
• UI consistency with other builds

See #168316 where at least 4 of us (@zanderso @jtmcdole @matanlurey @sigmundch) were confused.