Add logs to dormant member removal worker

In order to provide a better insight into dormant member removals, we
are adding logs to the removal worker

ee/app/workers/namespaces/remove_dormant_members_worker.rb

@@ -61,6 +61,7 @@ def namespaces_requiring_dormant_member_removal(limit = 1)
     def remove_dormant_members(namespace)
       dormant_period = namespace.namespace_settings.remove_dormant_members_period.days.ago
       admin_bot = ::Users::Internal.admin_bot
+      dormant_count = 0
 
       ::GitlabSubscriptions::SeatAssignment.dormant_in_namespace(namespace, dormant_period).find_each do |assignment|
         next if namespace.owner_ids.include?(assignment.user_id)
@@ -68,7 +69,19 @@ def remove_dormant_members(namespace)
         ::Gitlab::Auth::CurrentUserMode.optionally_run_in_admin_mode(admin_bot) do
           ::Members::ScheduleDeletionService.new(namespace, assignment.user_id, admin_bot).execute
         end
+
+        dormant_count += 1
       end
+
+      log_monitoring_data(namespace.id, dormant_count)
+    end
+
+    def log_monitoring_data(namespace_id, dormant_count)
+      Gitlab::AppLogger.info(
+        message: 'Processed dormant member removal',
+        namespace_id: namespace_id,
+        dormant_count: dormant_count
+      )
     end
   end
 end

ee/spec/workers/namespaces/remove_dormant_members_worker_spec.rb

@@ -38,6 +38,18 @@
             expect { perform_work }.to change { group.namespace_settings.reload.last_dormant_member_review_at }
           end
 
+          it 'logs monitoring data' do
+            allow(Gitlab::AppLogger).to receive(:info)
+
+            expect(Gitlab::AppLogger).to receive(:info).with(
+              message: 'Processed dormant member removal',
+              namespace_id: group.id,
+              dormant_count: 1
+            )
+
+            perform_work
+          end
+
           context 'when the dormant member is an owner of the group' do
             it 'does not remove the owner' do
               group.add_owner(dormant_assignment.user)