[Job Debugging] Container reservation when the job failed due to users' error.

[ydye]

What would you like to be added:

Container reservation when the user command fail to be executed. 

See the picture following, if the exit code of user's job command is a none zero value. That means something wrong happens.  And it's an users' error. We will catch the exit code and then sleep for a hardcode time. So that user is able to debug and find out the root cause why their job failed. 

Why is this needed:

Keep the environment of the failed job container for user to debug it.

Without this feature, how does the current module work：

In users' command, they can add a command to sleep if the previous job command failed. 

Components that may involve changes:

Restserver

Test Case:

Submit a job with debug mode

Please follow the detail message in this PR. #2225

The job command.

To better monitor the behavior, you should first make you job sleep some seconds, then exit with a none zero value. To ensure, whether it is reversed or not.