Address review: truncate tool definitions and clarify normalizer JSDoc

- Wrap GenAiAttr.TOOL_DEFINITIONS / tools_available toolDefinitions in truncateForOTel to avoid exceeding the 64KB OTel attribute cap with large tool catalogs.

- Drop misleading tool_search variant from toToolDefinitions JSDoc; the implementation requires a name and emits type:'function', so OpenAI client-side tool_search entries are intentionally skipped.