Swap conditions to reduce frequency of database query

The `Gitlab::Mirror.reschedule_immediately?` performs a rather heavy
query and it was detected that this is the major contributor to total
query time on GitLab.com (50% of total time is spent in this query!).

Context: https://gitlab.com/gitlab-org/gitlab-ce/issues/60524

ee/app/workers/repository_update_mirror_worker.rb

@@ -35,7 +35,7 @@ class RepositoryUpdateMirrorWorker
     fail_mirror(project, ex.message)
     raise UpdateError, "#{ex.class}: #{ex.message}"
   ensure
-    if !lease.exists? && Gitlab::Mirror.reschedule_immediately? && lease.try_obtain
+    if !lease.exists? && lease.try_obtain && Gitlab::Mirror.reschedule_immediately?
       UpdateAllMirrorsWorker.perform_async
     end
   end

ee/changelogs/unreleased/ab-60524-high-frequency-query.yml

+---
+title: Swap conditions to reduce frequency of database query
+merge_request: 11217
+author:
+type: performance