fix(NODE-5106): fix test MongoClient import

Co-authored-by: Neal Beeken <neal.beeken@mongodb.com>

Author: clemclx

test/integration/mongo_client.test.ts

@@ -1,7 +1,7 @@
 import { expect } from 'chai';
 import * as sinon from 'sinon';
 
-import { MongoClient } from '../../src';
+import { MongoClient } from '../mongodb';
 
 describe('MongoClient', () => {
   let client: MongoClient;