Remove uses of TransformComponent.ChildEntities (#22442)

* Make output of ChildEnumerator non-nullable

* Remove uses of ChildEntities

* poke tests

---------

Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Server/Shuttles/Systems/ShuttleSystem.FasterThanLight.cs

@@ -501,10 +501,10 @@ public sealed partial class ShuttleSystem
         var childEnumerator = xform.ChildEnumerator;
         while (childEnumerator.MoveNext(out var child))
         {
-            if (!_buckleQuery.TryGetComponent(child.Value, out var buckle) || buckle.Buckled)
+            if (!_buckleQuery.TryGetComponent(child, out var buckle) || buckle.Buckled)
                 continue;
 
-            toKnock.Add(child.Value);
+            toKnock.Add(child);
         }
     }