Shorten spacing interval between deleted groups

Similar to this issue and MR:

MR: !35046
Issue: #212645

Groups are also scheduled for deletion with a 5 minute
gap between them which is causing a large backlog
in groups/namespaces in QA runs.

ee/app/workers/adjourned_group_deletion_worker.rb

@@ -4,7 +4,7 @@ class AdjournedGroupDeletionWorker # rubocop:disable Scalability/IdempotentWorke
   include ApplicationWorker
   include CronjobQueue
 
-  INTERVAL = 5.minutes.to_i
+  INTERVAL = 10.seconds.to_i
 
   feature_category :authentication_and_authorization
 

ee/spec/workers/adjourned_group_deletion_worker_spec.rb

@@ -42,5 +42,16 @@
 
       worker.perform
     end
+
+    it 'schedules groups 10 seconds apart' do
+      group_marked_for_deletion_2 = create(:group_with_deletion_schedule,
+                                            marked_for_deletion_on: 14.days.ago,
+                                            deleting_user: user)
+
+      expect(GroupDestroyWorker).to receive(:perform_in).with(0, group_marked_for_deletion.id, user.id)
+      expect(GroupDestroyWorker).to receive(:perform_in).with(10, group_marked_for_deletion_2.id, user.id)
+
+      worker.perform
+    end
   end
 end