Fix DailySuffixTsv for testability, remove leaked DailySuffixTsv

It turns out that the reason using DailySuffixTsv was weird is that the SourceSpec test leaked a different one. Odd!

This removes that (a non-backwards compatible change, technically) and now the proper one is the only choice and seems to work properly.
Doesn't seem like it is testing much, I agree, but I guess they wanted to test equality against an identically configured class that wasn't the same object