Update xfail reason for no_variables test.

Author: jimf5

tests/test_otel.py

@@ -487,7 +487,7 @@ def test_variables(
             value = hexlify(getattr(span, value)).decode("utf-8")
         assert headers.get(name) == value
 
-    @pytest.mark.xfail(True, reason="otel variables are present when no trace")
+    @pytest.mark.xfail(reason="otel variables are present when trace is off")
     @pytest.mark.parametrize("idx", [10, 11], ids=["trace off"] * 2)
     @pytest.mark.parametrize(
         ("name", "value"),