fix: replace thrift_backend with backend in result set param

Signed-off-by: varun-edachali-dbx <varun.edachali@databricks.com>

Author: varun-edachali-dbx

tests/unit/test_fetches_bench.py

@@ -31,7 +31,7 @@ def make_dummy_result_set_from_initial_results(arrow_table):
         arrow_queue = ArrowQueue(arrow_table, arrow_table.num_rows, 0)
         rs = client.ResultSet(
             connection=None,
-            thrift_backend=None,
+            backend=None,
             execute_response=ExecuteResponse(
                 status=None,
                 has_been_closed_server_side=True,