Jekyll: Use non-minified assets when not running from GitHub Pages

Fixes #13575.
We can probably combine these into a single if/else, no? Like so:

```
{% if site.github %}
<script src="../dist/js/bootstrap.min.js"></script>
<script src="../assets/js/docs.min.js"></script>
{% else %}
<script src="../dist/js/bootstrap.js"></script>
<script src="../assets/js/vendor/holder.js"></script>
<script src="../assets/js/vendor/ZeroClipboard.min.js"></script>
<script src="../assets/js/src/application.js"></script>
{% endif %}
```