ancestors::new -> default (#17195)

runtime/benches/accounts.rs

@@ -238,7 +238,7 @@ fn bench_concurrent_read_write(bencher: &mut Bencher) {
                 let i = rng.gen_range(0, pubkeys.len());
                 test::black_box(
                     accounts
-                        .load_without_fixed_root(&Ancestors::new(), &pubkeys[i])
+                        .load_without_fixed_root(&Ancestors::default(), &pubkeys[i])
                         .unwrap(),
                 );
             }