Follow-up to hints part of
https://github.com/zed-industries/zed/pull/61523

Instead of appending to the chunk data, we have to replace as we always
get all hints for the entire chunk.
Given that we order and invalidate the requests by `Version`, this can
only happen when a racy requests from e.g. same file split or /refresh
and edit etc. happens.

Release Notes:

- N/A