What you are asking for isn't directly realated to rubrics. It sounds like what you want is to be able to bulk upload student submissions. I'm not aware of functionality that does this (you can bulk upload feedback files but that probably won't help)
I would suggest that you post a new discussion in the assignment forum here titled 'bulk upload assignment submissions' describing what you are looking for and someone might have some ideas, but I suspect you may need to pay a moodle developer to create this functionality for you (search for a local moodle partner to help with this)