feat(24.04): add ubuntu-keyring

[Meulengracht]

Proposed changes

Add the ubuntu-keyring package that bundles gpg keys neccessary for UC.

Forward porting

I can propose this for 24.10 as well

Checklist

• [x] I have read the contributing guidelines
• [x] I have tested my changes (see how)
• [x] I have already submitted the CLA form

[github-actions[bot]]

Diff of dependencies: None found.

---