title: django admin overriding delete_model not working with bulk delete
body: <p>I want to disable deleting for a specific model instance</p>
  <p>I overrided <code>delete_model</code> in the <code>ModelAdmin</code> as follows :</p>
  <pre><code>def delete_model(self, request, client):
      if client.schema_name == 'public':
          messages.set_level(request, messages.ERROR)
          messages.error(request, 'Suppression interdite pour la racine')
      else:
          super().delete_model(request, client)
  </code></pre>
  <p>It works when I click the delete button on change view</p>
  <p><a href="https://i.stack.imgur.com/GKahz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GKahz.png" alt="enter image description here" /></a><a href="https://i.stack.imgur.com/vy4DB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vy4DB.png" alt="enter image description here" /></a></p>
  <p>But not with bulk delete as the instance is deleted without preventing</p>
  <p><a href="https://i.stack.imgur.com/ofnaD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ofnaD.png" alt="enter image description here" /></a></p>
  <p>How can I fix this ? I also realized that <code>delete_model</code> is not called with bulk delete which makes a bit weird.</p>