[misc] migrate the app to the native mongo driver

acceptance tests to follow in a separate commit.

services/track-changes/test/acceptance/js/helpers/TrackChangesApp.js

@@ -13,6 +13,7 @@
  * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
  */
 const app = require('../../../../app')
+const { waitForDb } = require('../../../../app/js/mongodb')
 require('logger-sharelatex')
 const logger = require('logger-sharelatex')
 const Settings = require('settings-sharelatex')
@@ -29,9 +30,10 @@ module.exports = {
       return callback()
     } else if (this.initing) {
       return this.callbacks.push(callback)
-    } else {
-      this.initing = true
-      this.callbacks.push(callback)
+    }
+    this.initing = true
+    this.callbacks.push(callback)
+    waitForDb().then(() => {
       return app.listen(
         __guard__(
           Settings.internal != null
@@ -56,7 +58,7 @@ module.exports = {
           })()
         }
       )
-    }
+    })
   }
 }
 function __guard__(value, transform) {