Fixed bug in BloomCacheRedis::getConnection

* The array keys need to be re-indexed to avoid picking a deleted one

Change-Id: I3c22674a0194597598d66179bb5e3625da1dd38c
(cherry picked from commit 6c45ff18bc4717e1854f50aa95ac416b920f329d)
Merge "Fixed bug in BloomCacheRedis::getConnection" into wmf/1.24wmf22