eval_started event: change interface to traceID\tjobsetID

I was not going to break the interface until I noticed
the current implementation uses the string literal \t.

src/script/hydra-eval-jobset

@@ -861,7 +861,7 @@ sub checkJobset {
     my $tmpId = "${startTime}.$$";
 
     $db->storage->dbh->do("notify eval_started, ?", undef,
-                          join('\t', $tmpId, $jobset->get_column('project'), $jobset->name));
+                          join("\t", $tmpId, $jobset->get_column('id')));
 
     eval {
         checkJobsetWrapped($jobset, $tmpId);

src/script/hydra-notify

@@ -98,6 +98,7 @@ $listener->subscribe("build_queued");
 $listener->subscribe("build_started");
 $listener->subscribe("cached_build_finished");
 $listener->subscribe("cached_build_queued");
+$listener->subscribe("eval_started");
 $listener->subscribe("hydra_notify_dump_metrics");
 $listener->subscribe("step_finished");