agent: Don't render usage callouts when not using the Zed provider (#30025)

This PR makes it so we don't render the usage callouts when not using
the Zed provider.

Release Notes:

- Agent Beta: Changed usage callouts to only be displayed when using a
model through the Zed provider.
7a9165d5ceMarshall Bowers committed on 5/6/2025, 5:50:26 PM· committed by GitHubparent80236d0
1 file changedLine totals unavailable