Back out "Prepare findEviction to be extended for multiple memory tiers"

Summary:
Original commit changeset: 96b416b07e67

Original Phabricator Diff: D40360742 (32d0f81)

Reviewed By: jaesoo-fb

Differential Revision: D41240019

fbshipit-source-id: 873db84307129d1cae7e86ffab7523c5261b2043

Author: haowu14