[crud] The hidden attribute set on the custom delete button is overridden

[web-padawan]

Description

When using custom "delete" button and setting hidden attribute on it, the vaadin-crud removes it due to this logic:

web-components/packages/crud/src/vaadin-crud-mixin.js

Line 698 in e2523f9

deleteButton.toggleAttribute('hidden', isNew);

Expected outcome

Expected the "Delete" button to be always hidden when the attribute is set.

Minimal reproducible example

<vaadin-crud>
  <vaadin-button slot="delete-button" hidden>Deleting forbidden</vaadin-button>
</vaadin-crud>

<script type="module">
  import '@vaadin/crud';

  const crud = document.querySelector('vaadin-crud');
  crud.items = [
    {
      firstName: 'John',
      lastName: 'Doe',
    },
    {
      firstName: 'Jane',
      lastName: 'Doe',
    },
  ];
</script>

Steps to reproduce

1. Add the snippet above to the page
2. Open the editor
3. Note the delete button is still visible

Environment

Vaadin version(s): 24.x

Browsers

Issue is not browser related