Describe the bug

If a course has a number of students who are "Withdrawn", they will be hidden by default from the checkpoint gradeable interface for instructors & full access graders -- and simply hidden from limited access graders. tas & instructors have an option to "hide withdrawn students".

However when a student is hidden from this gradeable type, the are not renumbered, and the alternating line color is determined assuming they were visible.

For example:

student 2 in the first example, and students 1 & 4 in the second example are withdrawn.

Expected behavior
Let's re-number the students after removing the withdrawn students and color based on the updated numbers.