PLAT-28 : Disable enable_external_access for duckdb for finer controls

[k-anshul]

Checklist:

• [x] Covered by tests
• [x] Ran it and it works as intended
• [x] Reviewed the diff before requesting a review
• [x] Checked for unhandled edge cases
• [x] Linked the issues it closes
• [x] Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• [ ] Intend to cherry-pick into the release branch
• [x] I'm proud of this work!