fix(job-scheduler): validate if next delayed job exists

[roggervalf]

Why

2. What problem does it solve or improve? Jobs cannot be in more than 1 state, if we do not validate if a job already exists when a delayed job that is created by a job scheduler is promoted, we can have this job id in more than 1 state, i.e active and delayed or completed and delayed

How

Enter the implementation details here.

1. How did you implement this? Validate job key existence before trying to add this record

Additional Notes (Optional)

Any extra info here.