Fix: Use correct node group for add node search

Similar to e5a7470638, the tree currently being edited should be
used for polling and other tests, rather than the node tree at the root
of the node editor's path.

source/blender/editors/space_node/add_node_search.cc

@@ -160,7 +160,7 @@ static void add_node_search_update_fn(
 {
   AddNodeSearchStorage &storage = *static_cast<AddNodeSearchStorage *>(arg);
   if (storage.update_items_tag) {
-    bNodeTree *node_tree = CTX_wm_space_node(C)->nodetree;
+    bNodeTree *node_tree = CTX_wm_space_node(C)->edittree;
     storage.search_add_items.clear();
     gather_add_node_operations(*C, *node_tree, storage.search_add_items);
     storage.update_items_tag = false;