Leave it on there.  Then there'll be less to do later.

I did a code search for `world.reset`:

https://github.com/search?l=ruby&q=%22world.reset%22&ref=searchresults&type=Code

And it looks like there are some things relying on it.  When we do #1338 we should probably issue a deprecation warning from 2.99 and ensure there's a proper public API to do the resetting off of `RSpec`.