MB-24055 [Ephemeral]: disable Bloom filter

MB-24055 [Ephemeral]: disable Bloom filter

The Bloom filter is still enabled for Ephemeral buckets, however this
is a waste of memory; as it serves no purpose for Ephemeral buckets.

Disable it - as well as saving any maintenance cost, it also reduces
the RSS of an empty Ephemeral bucket from:

    57800 KB
to:

    44632 KB

Change-Id: I430ec84dbb7ff795141500aa76329b7ae5f5cd17
Reviewed-on: http://review.couchbase.org/77269
Reviewed-by: Manu Dhundi <manu@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>