fix test for .iter().sort() to include data to sort (#18127)

The test case `query_iter_sorts` was doing lots of comparisons to ensure
that various query arrays were sorted, but the arrays were all empty.

This PR spawns some entities so that the entity lists to compare not
empty, and sorting can actually be tested for correctness.

crates/bevy_ecs/src/query/iter.rs

@@ -2602,10 +2602,16 @@ mod tests {
     #[test]
     fn query_iter_sorts() {
         let mut world = World::new();
+        for i in 0..100 {
+            world.spawn(A(i as f32));
+            world.spawn((A(i as f32), Sparse(i)));
+            world.spawn(Sparse(i));
+        }
 
         let mut query = world.query::<Entity>();
 
         let sort = query.iter(&world).sort::<Entity>().collect::<Vec<_>>();
+        assert_eq!(sort.len(), 300);
 
         let sort_unstable = query
             .iter(&world)