Align nuxeo-document-distribution-chart for elasticsearch 5.6 upgrade

As mentionned in https://www.elastic.co/guide/en/elasticsearch/reference/2.4/search-aggregations-bucket-terms-aggregation.html

The ability to set size to 0, resulting in the size being set to Integer.MAX_VALUE, is deprecated, and will be removed in the next major release.

Indeed, the size params set to 0 used to mean an unlimited number of returned bucket. Now we must pass an explicit hight value when we want a big number of returned bucket.