[Docs] Remove boost parameter from intervals-query example (#43331)

The boost factor doesn't seem to be needed and can be removed.

docs/reference/query-dsl/intervals-query.asciidoc

@@ -40,7 +40,6 @@ POST _search
             }
           ]
         },
-        "boost" : 2.0,
         "_name" : "favourite_food"
       }
     }
@@ -298,4 +297,4 @@ POST _search
   }
 }
 --------------------------------------------------
-// CONSOLE
+// CONSOLE