These two apt.conf.d config files are installed by different packages
but have overlap in the configuration they set. Unfortunately if the
wrong one sets the flag to disable periodic updates it wins based on apt
conf's priority rules.
To ensure that we continue to auto update and handle different packages
supplying different config files we manage the entirety of the periodic
config in both of these files at the same time using a common source
file.
Change-Id: I5e408fd7c343adb1de9ec564fe430a6f31ecc360
6d3a281a42