MB-8903: Throw when failover log is too large

Change-Id: I2b294c2ab8b80d5fdd2216b3054e981beb7f13f3
Reviewed-on: http://review.couchbase.org/32325
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>