remove unused GoBeyond and ScriptCompletion level types

[davidsbailey]

Follow-on to #35239 . Removes two unused level types.

Testing story

• there are no level files for either level type
• there are no levels of type GoBeyond in staging, test, levelbuilder or production DB
• there was one level of type ScriptCompletion in levelbuilder and production DBs, named "Test Script Completion". it did not appear in any scripts. I removed that level from both of those environments and confirmed that none still exist in those environments.
• if someone does have "Test Script Completion" in their development DB, they could get a server error by trying to view that level directly via url like http://localhost-studio.code.org:3000/levels/12345, but that seems mostly harmless.

Reviewer Checklist:

• Tests provide adequate coverage
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[dmcavoy]

🎉 Love deleting old things! Thank you!

This made me remember we have a bunch of code from when we were exploring adding scratch (before sprite lab). I'm wondering if that should also be removed?

[davidsbailey]

This made me remember we have a bunch of code from when we were exploring adding scratch (before sprite lab). I'm wondering if that should also be removed?

I think those would be great to remove! If you can find it, I would say go for it.