Don't assign the owner of a PR

[foolip]

On web-platform-tests/wpt#18677 @wpt-pr-bot assigned me even though I sent the PR. That's not very helpful.

[foolip]

It looks like this shouldn't happen:

wpt-pr-bot/lib/metadata/choose-assignee.js

Line 16 in b6b7fd1

var reviewers = metadata.reviewersExcludingAuthor;

So the question then becomes why it did. The PR was initially a draft, might that explain it?

[jugglinmike]

That pull request was reviewed by its author, and as per gh-55, the script assigns the latest reviewer.

That review came hours after the pull request was opened, though. So the new question is: why didn't the bot assign a reviewer initially?

It's not that the pull request was a draft since (per gh-69) we know the script responds to such events.

[foolip]

Oh, I was just "reviewing" to get inline comments grouped together in a batch, I didn't even consider that activity as a review. But that explains what happened here, thanks!