Add max_concurrent_shard_requests to open PIT API (#4142)

Author: pquentin

output/openapi/elasticsearch-openapi.json

@@ -81,6 +81,12 @@
       ],
       "response": []
     },
+    "open_point_in_time": {
+      "request": [
+        "Request: query parameter 'max_concurrent_shard_requests' does not exist in the json spec"
+      ],
+      "response": []
+    },
     "reindex": {
       "request": [
         "Request: query parameter 'require_alias' does not exist in the json spec",

output/openapi/elasticsearch-serverless-openapi.json

@@ -19,6 +19,7 @@
 
 import { RequestBase } from '@_types/Base'
 import { ExpandWildcards, Indices, Routing } from '@_types/common'
+import { integer } from '@_types/Numeric'
 import { QueryContainer } from '@_types/query_dsl/abstractions'
 import { Duration } from '@_types/Time'
 
@@ -111,6 +112,11 @@ export interface Request extends RequestBase {
      * @server_default false
      */
     allow_partial_search_results?: boolean
+    /**
+     * Maximum number of concurrent shard requests that each sub-search request executes per node.
+     * @server_default 5
+     */
+    max_concurrent_shard_requests?: integer
   }
   body: {
     /**