Don't set non-recording span as current (#1527)

Author: alexmojaki

pydantic_ai_slim/pydantic_ai/agent.py

@@ -659,7 +659,7 @@ async def get_instructions(run_context: RunContext[AgentDepsT]) -> str | None:
             start_node,
             state=state,
             deps=graph_deps,
-            span=use_span(run_span, end_on_exit=True),
+            span=use_span(run_span, end_on_exit=True) if run_span.is_recording() else None,
             infer_name=False,
         ) as graph_run:
             yield AgentRun(graph_run)