Reduce I/O in build listings by only fetching required columns

Columns such as "longDescription" can be large, so fetching them
when they're not needed is wasteful.

src/lib/Hydra/Controller/Jobset.pm

@@ -83,7 +83,7 @@ sub jobsetIndex {
     # Last builds for jobset.
     $c->stash->{lastBuilds} = 
 	[ $c->stash->{jobset}->builds->search({ finished => 1 }, 
-            { order_by => "timestamp DESC", rows => 5 }) ];
+            { order_by => "timestamp DESC", rows => 5, columns => [@buildListColumns] }) ];
 }