Improve merge queue support in the CodeQL workflow

[mcdonnnj]

🗣 Description

This pull request adds better merge queue support to the CodeQL workflow which mirrors similar changes made to the build workflow in #177.

💭 Motivation and context

This might help ease merge queue issues. Even if it does not it will not harm anything and mirrors GitHub's documentation on supporting merge queues. I meant to push this change on top of #177 when I was trying to merge it up since the queue was dying on CodeQL results but I crossed my wires and forgot 🤦

🧪 Testing

Automated tests pass.

✅ Pre-approval checklist

• [x] This PR has an informative and human-readable title.
• [x] Changes are limited to a single goal - eschew scope creep!
• [x] All relevant type-of-change labels have been added.
• [x] I have read the CONTRIBUTING document.
• [x] These code changes follow cisagov code standards.
• [x] All relevant repo and/or project documentation has been updated to reflect the changes in this PR.
• [x] All new and existing tests pass.