[misc] mongodb: drop the getCollection helper

services/chat/app/js/mongodb.js

@@ -3,23 +3,20 @@ const { MongoClient, ObjectId } = require('mongodb')
 
 const clientPromise = MongoClient.connect(Settings.mongo.url)
 
-async function getCollection(name) {
-  return (await clientPromise).db().collection(name)
-}
-
 async function waitForDb() {
   await clientPromise
 }
 
 const db = {}
 waitForDb().then(async function () {
-  db.messages = await getCollection('messages')
-  db.rooms = await getCollection('rooms')
+  const internalDb = (await clientPromise).db()
+
+  db.messages = internalDb.collection('messages')
+  db.rooms = internalDb.collection('rooms')
 })
 
 module.exports = {
   db,
   ObjectId,
-  getCollection,
   waitForDb
 }