Remove unused route admin_development

Problem/Motivation

The admin_development only redirect to the /admin/structure/menu/ page, so at this time don't have any important use in the module.

admin_development:
  path: '/admin/development'
  defaults:
    _controller: '\Drupal\admin_toolbar_tools\Controller\ToolbarController::development'
    _title: 'Development'
  requirements:
    _permission: 'administer site configuration'

Only a redirect to:

 /**
   * Displays the administration link Development.
   */
  public function development() {
    return new RedirectResponse('/admin/structure/menu/');
  }

Proposed resolution

Remove admin_development route.

Remaining tasks

None.

User interface changes

None.

API changes

None.

Data model changes

None.