api: fix /eval/X/builds requiring 5*len(builds)+1 SQL queries

Prefetch related tables that get fetched as part of serialization to
JSON. Drop the `jobsetevals` field since making it efficient is trickier
(due to not using DBIx native relationships but instead a many_to_many
through a custom table). There is likely a way we could keep it and make
it efficient, but I'm not fluent enough in DBIx to know.

(cherry picked from commit cb10eef)

src/lib/Hydra/Controller/JobsetEval.pm

@@ -199,7 +199,9 @@ sub store_paths : Chained('evalChain') PathPart('store-paths') Args(0) {
 # Return full info about all the builds in this evaluation.
 sub all_builds : Chained('evalChain') PathPart('builds') Args(0) {
     my ($self, $c) = @_;
-    my @builds = $c->stash->{eval}->builds;
+    my @builds = $c->stash->{eval}->builds
+        ->search({},
+                 { prefetch => ['jobset', 'buildoutputs', 'buildproducts', 'buildmetrics'] });
     $self->status_ok(
         $c,
         entity => [@builds],

src/lib/Hydra/Schema/Result/Builds.pm

@@ -568,27 +568,21 @@ makeQueries('ForJobName', "and jobset_id = (select id from jobsets j where j.nam
 sub as_json {
   my ($self) = @_;
 
-  # After #1093 merges this can become $self->jobset;
-  # However, with ->jobset being a column on master
-  # it seems DBIX gets a it confused.
-  my ($jobset) = $self->search_related('jobset')->first;
-
   my $json = {
     id => $self->get_column('id'),
     finished => $self->get_column('finished'),
     timestamp => $self->get_column('timestamp'),
     starttime => $self->get_column('starttime'),
     stoptime => $self->get_column('stoptime'),
-    project => $jobset->get_column('project'),
-    jobset => $jobset->name,
+    project => $self->jobset->get_column('project'),
+    jobset => $self->jobset->get_column('name'),
     job => $self->get_column('job'),
     nixname => $self->get_column('nixname'),
     system => $self->get_column('system'),
     priority => $self->get_column('priority'),
     buildstatus => $self->get_column('buildstatus'),
     releasename => $self->get_column('releasename'),
     drvpath => $self->get_column('drvpath'),
-    jobsetevals => [ map { $_->id } $self->jobsetevals ],
     buildoutputs => { map { $_->name  => $_ } $self->buildoutputs },
     buildproducts => { map { $_->productnr => $_ } $self->buildproducts },
     buildmetrics => { map { $_->name => $_ } $self->buildmetrics },

t/Hydra/Controller/Build/api.t

@@ -67,7 +67,6 @@ subtest "validating the JSON representation of a build" => sub {
         finished => 1,
         id => $aggregateBuild->id,
         job => "aggregate",
-        jobsetevals => [ $aggregateBuild->jobsetevals->first->id ],
         nixname => "aggregate",
         priority => 100,
         releasename => undef,