docs: Update some docs and samples to use the new google-genai plugin

[ifielker]

Description here... Help the reviewer by:

• linking to an issue that includes more details
• if it's a new feature include samples of how to use the new feature
• (optional if issue link is provided) if you fixed a bug include basic bug details

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)