assistant2: Make `ContextStore::insert_*` methods private (#22989)

This PR makes the `insert_*` methods on the `ContextStore` private, to
reduce confusion with the public `add_*` methods.

Release Notes:

- N/A
40ecc38dd2Marshall Bowers committed on 1/10/2025, 10:50:33 PM· committed by GitHubparent1fcc9b3
3 files changedLine totals unavailable