apt::puppet: ensure => absent

We don't need to pin to the o=Ubuntu version, as we don't ship packages
in our repository anymore. ensure => absent both stanzas. Do not remove
the class just yet, but let it clean up on both production and Labs.

Change-Id: Id67b2270ec937fced0b06af4a875ef199da5a35b
apt: make per-host proxy conditional on $lsbdistid

Change-Id: Id6e56a7e7f2a11db1761220f7850a6b058eccd24