Delete page children tab dropdown toggle link has no text

Note that the same issue can be found in the restore template, it should be fixed the same way.

WCAG warnings in the test class [org.xwiki.flamingo.test.docker.AllIT]:
Validation in the test method [deletePageWithUsedClass]
Check for [org.xwiki.test.ui.po.DeletePageConfirmationPage] at http://xwikiweb:8080/xwiki/bin/delete/NestedDeletePageIT/deletePageWithUsedClass/WebHome.
Found [2] items

Links must have discernible text
Description: Ensures links have discernible text
Help URL: https://dequeuniversity.com/rules/axe/4.6/link-name?application=axeAPI
Help: Links must have discernible text
Impact: serious
Tags: cat.name-role-value, wcag2a, wcag412, wcag244, section508, section508.22.a, ACT

HTML element:
<a class="panel-collapse-carret" role="button" data-toggle="collapse" href="#panel-children" aria-expanded="false" aria-controls="panel-children"><span class="caret"></span></a>
Selector: [.panel-collapse-carret]
Fix all of the following:
Element is in tab order and does not have accessible text

Fix any of the following:
Element does not have text that is visible to screen readers
aria-label attribute does not exist or is empty
aria-labelledby attribute does not exist, references elements that do not exist or references elements that are empty
Element has no title attribute