Correct "getActiveBindings()" method name
Summary: This method was incorrectly renamed by D21628. See https://discourse.phabricator-community.org/t/unable-to-lease-host/4696.
Test Plan: Looked at it, will deploy etc.
Subscribers: yelirekim, PHID-OPKG-gm6ozazyms6q6i22gyam
Differential Revision: https://secure.phabricator.com/D21644