Revert 'drupalAutoButtons' => FALSE for modal

Problem/Motivation

Following the change in #3280047 🐛 Set 'drupalAutoButtons' => FALSE for modal to stop all buttons being moved into modal actions Needs review , nothing was actually fixed, but a bug was introduced in Gin Layout builder. Because the fix changes the layout for Media Library modal.

After testing the change with the latest Drupal and Gin, the initial issue is not reproduced.
But it introduces a bug in Layout Builder using Gin and Gin Layout Builder. The buttons are not visible.
The other side effect is that the UI is inconsistent in Modal flow.
In the Media Library Browse/Add, buttons are placed in the footer. In the Edit modal pop in, the button is in the content.

Here are some screenshots of my tests:
The button is missing in Gin Layout Builder

The multiple fields buttons are not affected by Drupal's dialog.ajax.js, because they have different class:

Steps to reproduce

1. Install Claro/Gin theme
2. Create a media type with Multiple value field (Text)
3. Create Media reference field in the Content entity
4. Enable Media library edit for media reference field and configure Modal for it
5. Open the Edit modal in the Content entity.

Proposed resolution

Revert the fix.

Test in Claro:

Test in Gin: