Fixing has_table() alone wasn't enough: get_columns() -- the actual
column-introspection call OceanBaseEngineSpec.get_columns() needs, and
what this test's second half exercises -- has the identical
connection.execute(raw string) bug, confirmed on real CI as the same
ObjectNotExecutableError. Patched the same way, reusing has_table()
correctly since self.has_table already resolves to the earlier patch.