Add 'dataset' size to cat indices and cat shards (#2840)

(cherry picked from commit 4cde24d)

Author: pquentin

output/openapi/elasticsearch-openapi.json

@@ -89,6 +89,13 @@ export class IndicesRecord {
    */
   'pri.store.size'?: string | null
 
+  /**
+   * total size of dataset (including the cache for partially mounted indices)
+   * @availability stack since=8.11.0 stability=stable
+   * @availability serverless stability=stable visibility=public
+   */
+  'dataset.size'?: string | null
+
   /**
    * size of completion
    * @aliases cs,completionSize

output/openapi/elasticsearch-serverless-openapi.json

@@ -53,6 +53,12 @@ export class ShardsRecord {
    * @aliases sto
    */
   'store'?: string | null
+  /**
+   * total size of dataset (including the cache for partially mounted indices)
+   * @availability stack since=8.11.0 stability=stable
+   * @availability serverless stability=stable visibility=public
+   */
+  'dataset'?: string | null
   /**
    * The IP address of the node.
    */