/etc/maas/templates/pxe/config.local.amd64.template is in maas-rack-controller 2.0.0~beta3+bzr4941-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | DEFAULT local
LABEL local
SAY Booting local disk ...
KERNEL chain.c32
APPEND hd0
|