Remove structured_output streaming #890
Description
Structured output currently invokes the callback_handler for events but the events emitted from Agent.structured_output are very provider & implementation-specific which leads to incosistencies:
- Right now bedrock emits a bunch of events because we implemented via tools; if we changed that, the events emitted would change.
- The other providers (like OpenAI) do not emit any events as they provide apis to perform structured_output
In #857, we re-implemented callback invocation to fix a backwards-incompatabile change that we made during the transition to internally-typed-events, but ultimately I don't think we should be invoking the callback for events in structured_output. This take represents a task to stop emitting events in the next major release.