fix: revert changes of timers/promises

Author: baileympearson

test/integration/server-selection/server_selection.prose.operation_count.test.ts

@@ -1,5 +1,5 @@
 import { expect } from 'chai';
-import { setTimeout as sleep } from 'timers/promises';
+import { setTimeout } from 'timers';
 import { promisify } from 'util';
 
 import { CommandStartedEvent } from '../../../src';
@@ -19,6 +19,8 @@ const failPoint = {
 
 const POOL_SIZE = 100;
 
+const sleep = promisify(setTimeout);
+
 async function runTaskGroup(collection: Collection, count: 10 | 100 | 1000) {
   for (let i = 0; i < count; ++i) {
     await collection.findOne({});