[Agentic Chat Integration] Update the structured content result of the Codebase Search tool

Context

The structured_content result of the Codebase Search tool has information that does not necessarily need to be exposed to anything that uses this tool. E.g.: the embeddings_v1 field, or the id field which is used by the Indexing pipeline to make sure each document has a unique content. We should remove these fields from the result.

Expand for screenshot of example result

Reference

Related discussion: #572264 (comment 2805564738)

Proposal

Remove the following fields:

• reindexing
• id
• type

Change the source field into different fields (see the chunk code for guide on how to split this field):

• blob_id
• start_byte
• start_line