Refactor Soft Delete Specs

Just for more discussion

This one was much harder. There's a few inline comments I want to make for discussion, but I'd also like input on what's left in https://github.com/OregonDigital/oregondigital/blob/feature/TrySoftDeleteSpecs/spec/features/soft_delete_spec.rb , which is primarily "display things that are queried". Any thoughts on how to pull that out? Or is this just the only way to avoid mucking about in Blacklight stuff?
I feel like you're specifying how this method is implemented in an indirect fashion. I don't mind asserting that an object calls another object's interface in situations where that's the binding interface, but asserting that an object calls a method on itself seems odd.

I would reword this to use `#persisted?` or something like that instead. You can obviously stub the `#persisted?` method if that's wanted.