test(smoke): mark test as read only (#15328)

Author: anshbansal

smoke-test/tests/metrics/test_metrics.py

@@ -9,13 +9,15 @@
 
 import logging
 
+import pytest
 import requests
 
 from tests.utils import get_gms_url
 
 logger = logging.getLogger(__name__)
 
 
+@pytest.mark.read_only
 def test_datahub_request_count_metric_present():
     """Test that the new datahub_request_count metric is present in Prometheus output."""
     gms_url = get_gms_url()