/usr/share/unattended-upgrades/20auto-upgrades-disabled is in unattended-upgrades 0.83.3.2+deb8u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | APT::Periodic::Update-Package-Lists "0";
APT::Periodic::Unattended-Upgrade "0";
|