chore: manifest.json should have stable json

[mutahhir]

Description

Ensure that the manifest.json file has stable output. Removes instances where test snapshots fail when no content has changed, but JSON.stringify shuffles object attribute order. Suggested by #3561

Checklist

• [ ] I have updated the PR title to match CDKTF's style guide
• [ ] I have run the linter on my code locally
• [ ] I have performed a self-review of my code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation if applicable
• [ ] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works if applicable
• [ ] New and existing unit tests pass locally with my changes