test(oracle): fix flaky test that assumes tables exist (#9898)

Closes #9897.

Author: cpcloud

ibis/backends/oracle/tests/test_client.py

@@ -82,7 +82,8 @@ def test_list_tables_schema_warning_refactor(con):
 def test_from_url():
     new_con = ibis.connect("oracle://ibis:ibis@localhost:1521/IBIS_TESTING")
 
-    assert new_con.list_tables()
+    result = new_con.sql('SELECT 1 AS "a"').to_pandas()
+    assert result.a.iat[0] == 1
 
 
 def test_invalid_port(con):