Refine when Props Bot runs

[desrosj]

What?

This refines when Props Bot runs and leaves comments a bit.

Why?

There are some scenarios where it's not appropriate for the bot to collect a list of contributors.

How?

When a PR is a draft, or closed, the bot should not comment with a list of contributors.

Reported in #58576.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core SVN

If you're a Core Committer, use this list when committing to wordpress-develop in SVN:

Props: desrosj, mamaduka.

GitHub Merge commits

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: desrosj <desrosj@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[desrosj]

Because the pull_request_target event runs in the context of the base of the pull request, rather than in the context of the merge commit, we'll likely need to merge this to properly test.

[Mamaduka]

Thanks for the quick follow-up, @desrosj!

Let's give it a try :)