Remove unused rubric type for CS Program

[Myranae]

Summary:

This removes an unused rubric type. The iframe tells the widget if the user's input is correct or not, so a rubric is not needed.
Additionally, validation happens after scoring, so it won't be possible to create a validation function for this widget at this time either.

Issue: LEMS-2440

Test plan:

• Confirm all checks pass
• Confirm widget still works as expected via a ZND (CS Program works via iFrame, which tens not to be testable locally)

[github-actions]

npm Snapshot: Published

Good news!! We've packaged up the latest commit from this PR (5fdf10a) and published it to npm. You
can install it using the tag PR1997.

Example:

yarn add @khanacademy/perseus@PR1997

If you are working in Khan Academy's webapp, you can run:

./dev/tools/bump_perseus_version.sh -t PR1997

[github-actions]

Size Change: 0 B

Total Size: 1.27 MB

ℹ️ View Unchanged

Filename	Size
packages/kas/dist/es/index.js	39 kB
packages/keypad-context/dist/es/index.js	760 B
packages/kmath/dist/es/index.js	4.27 kB
packages/math-input/dist/es/index.js	77.9 kB
packages/math-input/dist/es/strings.js	1.79 kB
packages/perseus-core/dist/es/index.js	1.48 kB
packages/perseus-editor/dist/es/index.js	688 kB
packages/perseus-linter/dist/es/index.js	22.2 kB
packages/perseus/dist/es/index.js	415 kB
packages/perseus/dist/es/strings.js	3.7 kB
packages/pure-markdown/dist/es/index.js	3.66 kB
packages/simple-markdown/dist/es/index.js	12.5 kB

_{compressed-size-action}

[jeremywiebe]

That makes sense. We'll just trust the frontend in this case for correctness.