replicaIndex is true by default in buckets

It looks like a change has occurred where now buckets are by default created with index replicas set to be equal to true.

E.g. on the cheshire-cat branch (7.0.x). Create the bucket:

$ curl -i -u Administrator:asdasd localhost:9000/pools/default/buckets -d name=b3 -d ramQuota=100 

HTTP/1.1 202 Accepted

Check the value of the replica_index property:

$ curl -s -u Administrator:asdasd localhost:9000/diag/eval -d '{ok, C} = ns_bucket:get_bucket("b3"), proplists:get_value(replica_index, C)'

true

I don't believe this used to be the case. At least I don't see this behavior on 6.6. I think this is a pretty significant regression - we should look at this quickly.