fix: clean up redundant test in dataframe_test

Author: shuoweil

tests/system/small/test_dataframe.py

@@ -5902,19 +5902,6 @@ def test_to_gbq_table_labels(scalars_df_index):
     assert table.labels["test"] == "labels"
 
 
-def test_to_gbq_obj_ref_persists(session):
-    # Test that saving and loading an Object Reference retains its dtype
-    bdf = session.from_glob_path(
-        "gs://cloud-samples-data/vision/ocr/*.jpg", name="uris"
-    ).head(1)
-
-    destination_table = "bigframes-dev.bigframes_tests_sys.test_obj_ref_persistence"
-    bdf.to_gbq(destination_table, if_exists="replace")
-
-    loaded_df = session.read_gbq(destination_table)
-    assert loaded_df["uris"].dtype == dtypes.OBJ_REF_DTYPE
-
-
 def test_dataframe_melt_multiindex(session):
     # Tests that `melt` operations via count do not cause MultiIndex drops in Arrow
     df = pd.DataFrame({"A": [1], "B": ["string"], "C": [3]})