Migrates search telemetry usage collector es client from legacy to new

src/plugins/data/server/search/collectors/fetch.ts

@@ -23,24 +23,20 @@ import { SharedGlobalConfig } from 'kibana/server';
 import { CollectorFetchContext } from 'src/plugins/usage_collection/server';
 import { Usage } from './register';
 
-interface SearchTelemetrySavedObject {
-  'search-telemetry': Usage;
-}
-
 export function fetchProvider(config$: Observable<SharedGlobalConfig>) {
-  return async ({ callCluster }: CollectorFetchContext): Promise<Usage> => {
+  return async ({ esClient }: CollectorFetchContext): Promise<Usage> => {
     const config = await config$.pipe(first()).toPromise();
-
-    const response = await callCluster<SearchTelemetrySavedObject>('search', {
-      index: config.kibana.index,
-      body: {
-        query: { term: { type: { value: 'search-telemetry' } } },
+    const { body } = await esClient.search(
+      {
+        index: config.kibana.index,
+        body: {
+          query: { term: { type: { value: 'search-telemetry' } } },
+        },
       },
-      ignore: [404],
-    });
-
-    return response.hits.hits.length
-      ? response.hits.hits[0]._source['search-telemetry']
+      { ignore: [404] }
+    );
+    return body.hits?.hits?.length > 0
+      ? body.hits.hits[0]._source['search-telemetry']
       : {
           successCount: 0,
           errorCount: 0,