fix: remove data-bs-toggle from LanguagePicker dropdown toggle

Bootstrap vanilla JS and react-bootstrap were both handling the dropdown,
causing the toggle to be unresponsive. react-bootstrap manages its own
state and does not need this attribute.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/web/frontend/js/shared/components/language-picker.tsx

@@ -24,7 +24,6 @@ function LanguagePicker({ showHeader } = { showHeader: false }) {
       <DropdownToggle
         id="language-picker-toggle"
         aria-label={t('select_a_language')}
-        data-bs-toggle="dropdown"
         className="btn-inline-link"
         variant="link"
       >