validation check on actual points

[katie-aisling]

Describe the bug
Its possible to give a student an unachievable points achieved value (e.g. 100 points for an A level) and the app will calculate the value added for that.

To Reproduce
Steps to reproduce the behaviour:

1. Use the user template to assign a student a high "actual points" and use the app as normal

Expected behaviour
The app should flag that the actual points are unachievable and remove that row from the user's data set