Revert to default source for Ansible role

[jsf9k]

🗣 Description

This pull request reverts to using Ansible Galaxy to source an Ansible role.

💭 Motivation and context

We were temporarily using a PR branch of this role, but that is no longer necessary now that gantsign/ansible-role-visual-studio-code#244 has been merged.

Resolves #153.

🧪 Testing

All automated tests pass. I also built a staging AMI with this change and verified that it functions as expected.

✅ 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 new and existing tests pass.

✅ Pre-merge checklist

• [x] Finalize version.

✅ Post-merge checklist

• [x] Create a release.