Revert "Add note that get_failover_log/2 is only used for testing"

This reverts commit 62571df235ac0864cf2f621055267e4f9023fa02.

Change-Id: I50a06f11b2d37359cba8d4454bc7ed8b4925b5c6
Reviewed-on: http://review.couchbase.org/34177
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: Volker Mische <volker.mische@gmail.com>