MB-10182 correctly handle RAM quota for sample buckets

... during the initial cluster setup

Change-Id: I55e8d281fd562c859c761fcb8191cd0e150d00be
Reviewed-on: http://review.couchbase.org/35123
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>