Update ns_server repo in toy-indexing.xml

Change-Id: I2952434e7c036c1ca7c00ae3a967652f91996c21
Reviewed-on: http://review.couchbase.org/42322
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: Sarath Lakshman <sarath@couchbase.com>