Update test_preserve_leading_zeros.py

Author: dxdc

pandas/tests/io/parser/test_preserve_leading_zeros.py

@@ -39,7 +39,4 @@ def test_leading_zeros_preserved_with_dtype_str(all_parsers, request):
             # Known issue: pyarrow engine strips leading zeros even with dtype=str.
             request.node.add_marker(
                 pytest.mark.xfail(reason=f"failed assertions: {exc}", strict=False)
-            )
-            assert False, "trigger xfail for pyarrow"
-        else:
-            raise
+        raise