Added remove_old_jobs api with unittest

The remove_old_jobs will do remove old jobs follow conditions
- IF ( job does not belong to any group OR group of job has all jobs which executed.)
   AND job was executed AND job was executed before (default 30 days)
then create new job with time schedule time is (executed datetime + 8 hours), 8 hours is default

* Not finish
- Migrations when use with other service is not work, case of using django-async on service such as dd.

* Not include
- Migration step that call command to migrate async initial step with option fake