shorter session timeout for UDP


git-svn-id: https://gnunet.org/svn/gnunet@31298 140774ce-b5e7-0310-ab8b-a85725594a96
-dead

git-svn-id: https://gnunet.org/svn/gnunet@31299 140774ce-b5e7-0310-ab8b-a85725594a96