Fix edge-case bug in "Issue Trigger" workflow

[t-will-gillis]

Fixes #8634

What changes did you make?

• In preliminary-update-comment.js added filter to remove PRs

Why did you make the changes (we will use this info to test)?

• We need to ensure that only issues are returned in the query so that if a dev assign themselves to their own PR, the results do not include it- this will cause GraphQL to return an error and the automation checks will fail.

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From your project repository, check out a new branch and test the changes.

git checkout -b t-will-gillis-fix-bug-issue-trigger-8634 gh-pages
git pull https://github.com/t-will-gillis/website.git fix-bug-issue-trigger-8634