upkeep: Don't depend on `r2dii.data` for unit tests

[jdhoffa]

What this is likely to look like in practice is:

• Removing all regression tests for adequately tested functions (what does adequately tested mean?)
• May end up being a dangerous change, but I think a desirable one

@AlexAxthelm do you have any experience or knowledge around how to ensure a "safe removal" of a regression test? Or rather, ensuring that the function has adequate test coverage prior to doing so?

AB#9906