aptrepo: un-change conf/incoming
Ie259b939971a5af switched this to make use of the template that existed
before but was not in use.
This resulted in a diff compared to existing setup on carbon though:
< TempDir: /tmp
< Allow: precise-wikimedia trusty-wikimedia jessie-wikimedia precise>precise-wikimedia trusty>trusty-wikimedia jessie->jessie-wikimedia
This fixes that so that carbon is like it was before.