fix: close db connections after running jobs from command line.

[andershermansen]

What?

Exit process after payload jobs:run without cron is executed

Why?

I would expect the payload jobs:run command to exit normally after execution. With mongodb this is not the case as database connections are open so the node process itself will not exit.

How?

Execute payload.db.destroy to close all db connections after queue is execution is done.

Fixes: #9851