Summary:
deleterandom tests are too fast to get good signal, e.g.
--deletes=31250 in 0.170 seconds vs. --reads=1500000 in 288.491
seconds for readrandom. Removing the special handling (unknown
motivation in faa7eb3b) should suffice.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10437

Test Plan: watch continuous results

Reviewed By: ltamasi

Differential Revision: D38261185

Pulled By: pdillinger

fbshipit-source-id: 0f1b1b19efccda5689027d36cc2f01307f36031d