MB-23530: Prevent replace with CAS on deleted item

MB-23530: Prevent replace with CAS on deleted item

Against an ephemeral bucket or full eviction persistent bucket, a
replace operation could erroneously succeed if the correct CAS value was
given. A replace with a CAS resolves internally to OPERATION_CAS, which
is treated in the same manner as OPERATION_SET.

Prior to this change, we checked if an item was previously deleted if
the CAS did _not_ match, but even if the CAS is /correct/ a replace with
a CAS should fail if the old item is deleted.

The set should only be rejected if the new item is /not/ deleted, to
avoid breaking the delete implementation described in
http://review.couchbase.org/#/c/76119.

Change-Id: Id1eeaeb5326b7a143c7213f07c774f02623bff8d
Reviewed-on: http://review.couchbase.org/76261
Reviewed-by: Daniel Owen <owend@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>