Cleanup Vertex + Chat (#2553)
* Cleanup Vertex + Chat
* logprobs defaults to false.
* Parameters are optional
* Fix docs.
* Changing back this logprobs default.
* Fixup doc.
* Let's debug that.
* Not unstable.
* Updating Cargo ?
* Wat?
* Dummy change.
* Trying some other install.
* Trying smething.
* Revert everything.
* Update Cargo lock.
* Fixing the pre-commit after rebase.
