install_server: split out reprepro to module aptrepo
Split the reprepro role out of the install_server module
as Faidon said on T132757.
Merge apt_repository into init.pp.
Rename module to "aptrepo", role to aptrepo::wikimedia.
Remove all the duplicate definitions of files and files
that had been replaced by templates.
Still need to check what's going on with "distributions vs.
distributions.erb" and "incoming vs. incoming.erb".
Bug:T132757
Change-Id: Ie259b939971a5affed178ed25c31373de1110e57