Remove unused imports and fix syntax formatting in DropzoneController files.

Author: Carlos Hernández

src/Dropzone/assets/src/controller.ts

@@ -22,7 +22,7 @@ export default class extends Controller {
         'previewClearButton',
         'previewFilename',
         'previewImage',
-        'previewContainer'
+        'previewContainer',
     ];
 
     files: Map<string, File> = new Map<string, File>();

src/Dropzone/assets/test/unit/controller.test.ts

@@ -9,7 +9,6 @@
 
 import { Application, Controller } from '@hotwired/stimulus';
 import { getByTestId, waitFor } from '@testing-library/dom';
-import user from '@testing-library/user-event';
 import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 import { clearDOM, mountDOM } from '../../../../../test/stimulus-helpers';
 import DropzoneController from '../../src/controller';