Remove legacy computer migration infrastructure, it's ancient

[kevingranade]

Summary

None

Purpose of change

While trying to track down a mapgen bug I came to suspect this conversion infrastructure. It didn't end up being the cause, but now that I'm looking it's really ancient so it's tome to go.

Describe the solution

Remove the migration code that was introduced in 0813ad46e45f47ccdab369cb270b2e627e9de9e5 over four years ago.