fix(ui): delay removal of jobs in the progress bar to avoid dead locks

Description

We often faced a deadlock in applications showing a progress bard, at the end of a job.

The deadlock occurred because of the following situation:

progress_bar::update_widgets()	progress_bar::show_job()::add_state_hook()
lock the progress bar	lock the job (higher in stack in ~jobs::observer)
lock the job (get_state())	lock the progress bar

To overcome the issue, we delayed removing the job from the widgets and moved it to the first thread using a task.

How to test it?

It was quite hard to catch actually. Stress testing the affecting applications might be the only way.