Stop generating llms.txt files for Chainlink Functions and Chainlink Automation

Problem

We generate llms.txt and llms-full.txt documentation bundles for every product section, including Chainlink Functions and Chainlink Automation. For these two products we are steering developers toward CRE for new use cases, so we do not want LLMs pulling in and focusing on the full Functions/Automation documentation bundles.

Today this happens because:

• src/config/llms.ts lists chainlink-functions and chainlink-automation in SUPPORTED_LLM_SECTIONS, so generate-llms.ts produces llms-full.txt for them (and the [section]/llms-full.txt route serves them, and validate-llms.ts expects them).
• Hand-authored llms.txt product indexes exist for both under src/content/, are synced into public/ by sync-product-llms.ts, and are linked from the root public/llms.txt index.

Desired outcome

• Remove Chainlink Functions and Chainlink Automation from llms.txt generation.
• Delete the already-generated llms-full.txt and the hand-authored llms.txt index files for both products (including the synced public/ copies).
• Remove their entries from the root public/llms.txt index.

Note: this only removes the LLM bundles — the underlying product documentation pages are unchanged.