Libraries with dependencies may cause race conditions with #lazy_builders

I've encountered a race condition when using a lazy builder that renders an element with an attached script that includes dependencies.

In this case I'm using a library like this:

editor:
  version: "1.0.0"
  js:
    js/editor.js: {}
  dependencies:
    - core/ckeditor

The issue is that dynamically added scripts are loaded asynchronously by default (see async). As a result in my example above it is possible for editor.js to be processed before ckeditor.js despite them being added to the page in the correct order resulting in a JS error.

This issue can be mitigated by attaching the libraries used by the lazy builder to the page after the lazy builder element so that it does not need to be added when replacing the placeholder.

$output['form'] = $lazy_builder;
$output['#attached']['library'][] = 'my_module/editor';
return $output;

Proposed Resolution

This should be preventable by adding an async="false" to all script tags loaded through the Drupal AJAX api from libraries.

Steps to Reproduce

I was able to reproduce this issue with and without JS aggregation, however with aggregation it was necessary to force my 2 JS files to load simultaneously by adding 10-20 image requests at the top of the page. CKEditor is a useful example dependency because of it's 550KB filesize.