Fix restoration of sub-sub children

Steps to reproduce

1. create the following structure under the Workspace

   WorkspaceRoot
   | - WS
     | - folder 1
       | - folder 2
         |- folder 3
           | - file 4
   

1. trash the top folder "folder 1"

   curl -s -X POST -u Administrator:Administrator --header "Content-Type: application/json+nxrequest" http://localhost:8080/nuxeo/site/automation/Document.Trash  -d '{"input": "doc:/default-domain/workspaces/WS/folder 1"}'
   

1. observe all documents are in deleted state
2. untrash the top folder "folder 1"

   curl -s -X POST -u Administrator:Administrator --header "Content-Type: application/json+nxrequest" http://localhost:8080/nuxeo/site/automation/Document.Untrash  -d '{"input": "doc:/default-domain/workspaces/WS/folder 1"}'
   

1. observe that only the top folder and its direct child (folder 1 and folder 2) have been restored. The sub-sub children are still trashed

Expected behavior: all documents are restored from the trash