Use GitlabShellWorker.perform_async for housekeeping

app/controllers/projects_controller.rb

@@ -172,14 +172,10 @@ def unarchive
   end
 
   def housekeeping
-    status = ::Projects::HousekeepingService.new(@project).execute
+    ::Projects::HousekeepingService.new(@project).execute
 
     respond_to do |format|
-      if status
-        flash[:notice] = "Housekeeping finished successfully."
-      else
-        flash[:alert] = "Housekeeping failed."
-      end
+      flash[:notice] = "Housekeeping successfully started."
       format.html { redirect_to project_path(@project) }
     end
   end

app/services/projects/housekeeping_service.rb

@@ -14,7 +14,7 @@ def initialize(project)
     end
 
     def execute
-      gitlab_shell.gc(@project.path_with_namespace)
+      GitlabShellWorker.perform_async(:gc, @project.path_with_namespace)
     end
   end
 end