agent: Allow all settings in the thread to apply immediately (#51762)

Before we kind of had it mixed: you could change thinking but not model
etc. We brute forced a solution by disabling, but it seems better to
just allow all of them to be updated whenever we would build the
request.

Release Notes:

- N/A
546c70aecaBen Brandt committed on 3/17/2026, 3:07:26 PM· committed by GitHubparentef40f21
5 files changedLine totals unavailable