Lower the prio of archiving jobs to avoid piling up finalize jobs

This reverses the prio of archiving and finalize jobs so finalize jobs are
now more important. This makes sense because finalize jobs are also
invoking hook scripts and are therefore more important than archiving which
has less notable consequences if delayed.

Related ticket: https://progress.opensuse.org/issues/190344

Author: Martchus

lib/OpenQA/Task/Job/Limit.pm

@@ -53,7 +53,7 @@ sub _limit ($job, $args = undef) {
 
     my $groups = $schema->resultset('JobGroups');
     my $gru = $app->gru;
-    my %options = (priority => 0, ttl => 2 * ONE_DAY);
+    my %options = (priority => -20, ttl => 2 * ONE_DAY);
     while (my $group = $groups->next) {
         my $preserved_important_jobs;
         $group->limit_results_and_logs(\$preserved_important_jobs);