Adding new queue metric fields to mapping (elastic/x-pack-elasticsearch#3949)

This will allow these fields to be used in aggregations by Monitoring UI code

Original commit: elastic/x-pack-elasticsearch@6ce0aec

Author: ycombinator

plugin/core/src/main/resources/monitoring-logstash.json

@@ -286,6 +286,12 @@
                     },
                     "type": {
                       "type": "keyword"
+                    },
+                    "max_queue_size_in_bytes": {
+                      "type": "long"
+                    },
+                    "queue_size_in_bytes": {
+                      "type": "long"
                     }
                   }
                 },