assistant2: Prevent sending messages when the button is disabled (#26722)

This PR updates the `Chat` action handler to prevent sending messages in
the states when the submit button is disabled.

Release Notes:

- N/A
22f1429f97Marshall Bowers committed on 3/13/2025, 8:49:21 PM· committed by GitHubparent6bdd2cf
1 file changedLine totals unavailable