Remove the delayed start functionality of jobs, as it's not used.

[apozsuse]

The code has implemented the delayed start functionality (iso timestamp/watchdog). This has never been used so it's something we could consider removing to simplify code.

[rjschwei]

Well, we have to be careful with "never been used". It has never been used by us. This is a public project and we do not know if other people use mash and whether or not they use the delayed start option for jobs. One way to remove the code would be to add a deprecation warning and see if we get any comments.