Focus always on top when adding/removing items in blocks using Layout Builder

As per comment https://www.drupal.org/project/drupal/issues/3471686#comment-15754893 🐛 CSS "form-item__label" inconsistent on node edit forms Needs review

Changes are made on 11.x (our main development branch) first, and are then back ported as needed according to our policies.

So changing the version to 11.x after verifying that this issue is reproducible in 11.x version.

I found one similar issue https://www.drupal.org/project/drupal/issues/3100133 🐛 Ajax replace inside a modal causes the current field to lose focus. Needs work . As per a comment in that ticket,

Some of the underlying logic was changed in #3397785: Dialog focus is returned to dialog instead of first tabbable element on dialog AJAX update

And I think the changes in https://www.drupal.org/project/drupal/issues/3397785 🐛 Dialog focus is returned to dialog instead of first tabbable element on dialog AJAX update Fixed caused this new issue. I found one patch in the comment section https://www.drupal.org/project/drupal/issues/3397785#comment-15665315 🐛 Dialog focus is returned to dialog instead of first tabbable element on dialog AJAX update Fixed which fixes this issue. I'm raising it as an MR here. But I think those changes were made for D10 when the 'Add field' section of paragraphs were in a modal box. In D11, it is a separate page. So do we really need those code which is introducing the new focus issues in layout builder?

Should be able to add a javascript or nightwatch test to verify focus.