Avoid cleaning up Owner of YGNode during clonning

Summary:
This diff refactors the cloning mechanism for YogaNode used from Fabric UI renderer and RN iOS graphs.
Previously, we were cleaning the owner of the child's cloned node inside the C++ implementation of YogaNode. This was a mistake because this modified the last commited YogaTree, causing side effect in RN iOS graphs.

Reviewed By: shergin

Differential Revision: D8672627

fbshipit-source-id: c9902d00690e0361fd58aed84b506c42258bd995

yoga/Yoga.cpp

@@ -244,9 +244,6 @@ YGNodeRef YGNodeClone(YGNodeRef oldNode) {
       oldNode->getConfig(),
       node != nullptr,
       "Could not allocate memory for node");
-  for (auto &item : oldNode->getChildren()) {
-    item->setOwner(nullptr);
-  }
   gNodeInstanceCount++;
   node->setOwner(nullptr);
   return node;