Fix wrong call to ProjectCacheWorker.perform

It's either ProjectCacheWorker#perform or
ProjectCacheWorker.perform_async!
Signed-off-by: Rémy Coutable <remy@rymai.me>

changelogs/unreleased/27516-fix-wrong-call-to-project_cache_worker-method.yml

+---
+title: Fix wrong call to ProjectCacheWorker.perform
+merge_request: 8910
+author:

lib/tasks/gitlab/import.rake

@@ -63,7 +63,7 @@ namespace :gitlab do
 
             if project.persisted?
               puts " * Created #{project.name} (#{repo_path})".color(:green)
-              ProjectCacheWorker.perform(project.id)
+              ProjectCacheWorker.perform_async(project.id)
             else
               puts " * Failed trying to create #{project.name} (#{repo_path})".color(:red)
               puts "   Errors: #{project.errors.messages}".color(:red)