fix(metrics-layer): Incorrect metrics layer tests (#54046)

- Fixes some tests that were setup incorrectly with the incorrect parent
test

tests/snuba/api/endpoints/test_organization_events_mep.py

@@ -2297,3 +2297,7 @@ class OrganizationEventsMetricsEnhancedPerformanceEndpointTestWithMetricLayer(
     @pytest.mark.xfail(reason="Not supported")
     def test_time_spent(self):
         super().test_time_spent()
+
+    @pytest.mark.xfail(reason="Not supported")
+    def test_http_error_rate(self):
+        super().test_http_error_rate()