fix: add exclude_list to @trace_class on high-frequency event classes

Addresses #1034 — the @trace_class decorator on EventQueue and related classes
generates 1500+ spans per LLM streaming session from high-frequency internal
methods (enqueue_event, dequeue_event, task_done, etc.).

Added exclude_list to @trace_class on:
- EventQueueLegacy: excludes enqueue_event, dequeue_event, task_done, is_closed
- EventQueueSource: excludes enqueue_event, dequeue_event, task_done, is_closed
- EventConsumer: excludes consume_all
- InMemoryQueueManager: excludes add, get, create_or_tap

This reduces tracing spans from 1500+ to ~53 per session (97% reduction) while
preserving useful RequestHandler-level traces. The existing exclude_list
mechanism in trace_class is used — no new API surface or breaking changes.

Author: naveenkumarbaskaran

src/a2a/server/events/event_consumer.py

@@ -18,7 +18,10 @@
 logger = logging.getLogger(__name__)
 
 
-@trace_class(kind=SpanKind.SERVER)
+@trace_class(
+    kind=SpanKind.SERVER,
+    exclude_list=['consume_all'],
+)
 class EventConsumer:
     """Consumer to read events from the agent event queue."""
 

src/a2a/server/events/event_queue.py

@@ -93,7 +93,10 @@ async def enqueue_event(self, event: Event) -> None:
         """
 
 
-@trace_class(kind=SpanKind.SERVER)
+@trace_class(
+    kind=SpanKind.SERVER,
+    exclude_list=['enqueue_event', 'dequeue_event', 'task_done', 'is_closed'],
+)
 class EventQueueLegacy(EventQueue):
     """Event queue for A2A responses from agent.
 

src/a2a/server/events/event_queue_v2.py

@@ -20,7 +20,10 @@
 logger = logging.getLogger(__name__)
 
 
-@trace_class(kind=SpanKind.SERVER)
+@trace_class(
+    kind=SpanKind.SERVER,
+    exclude_list=['enqueue_event', 'dequeue_event', 'task_done', 'is_closed'],
+)
 class EventQueueSource(EventQueue):
     """The Parent EventQueue.
 

src/a2a/server/events/in_memory_queue_manager.py

@@ -9,7 +9,10 @@
 from a2a.utils.telemetry import SpanKind, trace_class
 
 
-@trace_class(kind=SpanKind.SERVER)
+@trace_class(
+    kind=SpanKind.SERVER,
+    exclude_list=['add', 'get', 'create_or_tap'],
+)
 class InMemoryQueueManager(QueueManager):
     """InMemoryQueueManager is used for a single binary management.