/usr/share/lxc/config/ubuntu.lucid.conf is in lxc-templates 2.0.7-0ubuntu1~16.04.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# Ubuntu 10.04 LTS doesn't have /dev/lxc/ lxc.devttydir =