Update skipped repo groups structure for variant analysis

[charisk]

The structure returned from the API has changed so this PR updates the relevant models. See internal linked issue for details.

Checklist

N/A: Code not in use yet.

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.