feat(ui,api): add guidance as a default setting option for FLUX models

[maryhipp]

Summary

• Update default settings for FLUX models to include Guidance, and to exclude CFG, CFG rescale multiplier, VAE precision, and schedulers since we do not yet support those in the UI

Related Issues / Discussions

QA Instructions

Merge Plan

Checklist

• [ ] The PR has a short but descriptive title, suitable for a changelog
• [ ] Tests added / updated (if applicable)
• [ ] Documentation added / updated (if applicable)