Move most of AddBuilds to hydra-eval-jobset

Having this stuff in a separate module is a remnant of the time when
hydra-server could add builds to the queue directly. This is no longer
the case.

src/lib/Hydra/Controller/Build.pm

@@ -6,7 +6,6 @@ use warnings;
 use base 'Hydra::Base::Controller::NixChannel';
 use Hydra::Helper::Nix;
 use Hydra::Helper::CatalystUtils;
-use Hydra::Helper::AddBuilds;
 use File::stat;
 use File::Slurp;
 use Data::Dump qw(dump);