Describe the bug
The Autograding Testcases page has 4 buttons, when it could be condensed to just 2:

The Regrade Active Version button should be an element inside of Toggle Dropdown, but instead it is clickable, while other elements are abstracted to the dropdown.

Expected behavior

The Regrade Active Version and Toggle Dropdown button should be combined into a single button that, on click, presents the user with each of the options they have.

The fix for this is almost the same as #12348, where this logic was resolved on the Student Grading Details page:

Before:

After

This pull request is a great reference for the solution here.

To Reproduce
Steps to reproduce the behavior:

1. Find any gradeable with autograding in the Sample course.
2. Enter the Student Grading Details page for that gradeable
3. Click on a specific student's grading
4. Go to the Autograding tab
5. See buttons