fix: enable automatic exception recording on MCP spans

Remove record_exception=False and set_status_on_exception=False from
create_mcp_client_span. Let OTel handle exception recording and status
setting automatically. The manual set_mcp_span_error calls for tools/call
still correctly set error.type (which OTel's automatic handling doesn't
touch), so tool_error is preserved.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/packages/core/agent_framework/observability.py

@@ -2053,8 +2053,8 @@ def create_mcp_client_span(
     with trace.use_span(
         span=span,
         end_on_exit=True,
-        record_exception=False,
-        set_status_on_exception=False,
+        record_exception=True,
+        set_status_on_exception=True,
     ) as current_span:
         yield current_span