Remove Flog
This MR removes the flog gem and its associated rake task as we use the ABC Metrics Rubocop to accomplish the same thing. There's not really any reason to have it anymore.
The rest of this MR is kept for posterity and is no longer relevant.
After a few months of flog/flay failing silently - and now a week of them failing loudly - I think it's safe to say we don't care enough about flog/flay for them to be worth keeping.
If you'd like to keep them around, speak now or forever hold your peace :)
See also #17858 (closed).