Change auto-model default batch size

[charisk]

Lowering the batch size to allow higher number of requests required for new functionality.

Basically due to sources we now need double the number of LLM requests, and because we havent increased parallelism we need to half the number of candidates.

Checklist

N/A:

• 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.

[starcke]

👍