test: suppress expected error logs in SSE test

Use pytest's caplog fixture to suppress ERROR logs when deliberately
triggering errors in test_sse_generator_error_before_response_starts.
This keeps test output clean while still validating error handling behavior.

tests/unit/server/test_sse.py

@@ -5,12 +5,21 @@
 # the root directory of this source tree.
 
 import asyncio
+import logging  # allow-direct-logging
 from unittest.mock import AsyncMock, MagicMock
 
+import pytest
+
 from llama_stack.apis.common.responses import PaginatedResponse
 from llama_stack.core.server.server import create_dynamic_typed_route, create_sse_event, sse_generator
 
 
+@pytest.fixture
+def suppress_sse_errors(caplog):
+    """Suppress expected ERROR logs for tests that deliberately trigger SSE errors"""
+    caplog.set_level(logging.CRITICAL, logger="llama_stack.core.server.server")
+
+
 async def test_sse_generator_basic():
     # An AsyncIterator wrapped in an Awaitable, just like our web methods
     async def async_event_gen():
@@ -70,7 +79,7 @@ async def test_sse_generator_client_disconnected_before_response_starts():
     assert len(seen_events) == 0
 
 
-async def test_sse_generator_error_before_response_starts():
+async def test_sse_generator_error_before_response_starts(suppress_sse_errors):
     # Raise an error before the response starts
     async def async_event_gen():
         raise Exception("Test error")