[Files] Fix flaky file creation and deletion tests (elastic#141753)

* set has content to false

* [revert this] only run the flaky test

* remove .only

x-pack/plugins/files/server/file_client/integration_tests/es_file_client.test.ts

@@ -11,11 +11,7 @@ import { createEsFileClient } from '../create_es_file_client';
 import { FileClient } from '../types';
 import { FileMetadata } from '../../../common';
 
-/**
- * This file client is using Elasticsearch interfaces directly to manage files.
- */
-// FLAKY: https://github.com/elastic/kibana/issues/139565
-describe.skip('ES-index-backed file client', () => {
+describe('ES-index-backed file client', () => {
   let esClient: TestEnvironmentUtils['esClient'];
   let fileClient: FileClient;
   let testHarness: TestEnvironmentUtils;
@@ -197,6 +193,9 @@ describe.skip('ES-index-backed file client', () => {
       })
     );
 
-    await Promise.all([fileClient.delete({ id: id1 }), fileClient.delete({ id: id2 })]);
+    await Promise.all([
+      fileClient.delete({ id: id1, hasContent: false }),
+      fileClient.delete({ id: id2, hasContent: false }),
+    ]);
   });
 });