Update confirmation button variant and label

Changed the button variant in the confirmation popup of Unprotect tag
to danger variant (Red). Also, the label of the button is updated
to "Unprotect tag" instead of just "OK".

Changelog: changed

app/views/projects/protected_tags/shared/_protected_tag.html.haml

@@ -19,4 +19,4 @@
 
   - if can? current_user, :admin_project, @project
     %td
-      = link_to 'Unprotect', [@project, protected_tag, { update_section: 'js-protected-tags-settings' }], data: { confirm: 'Tag will be writable for developers. Are you sure?' }, method: :delete, class: 'gl-button btn btn-danger-secondary'
+      = link_to 'Unprotect', [@project, protected_tag, { update_section: 'js-protected-tags-settings' }], aria: { label: s_('ProtectedTags|Unprotect tag') }, data: { confirm: 'Tag will be writable for developers. Are you sure?', confirm_btn_variant: 'danger' }, method: :delete, class: 'gl-button btn btn-danger-secondary'

locale/gitlab.pot

@@ -29334,6 +29334,9 @@ msgstr ""
 msgid "ProtectedEnvironment|Your environment has been unprotected"
 msgstr ""
 
+msgid "ProtectedTags|Unprotect tag"
+msgstr ""
+
 msgid "ProtectedTags|default"
 msgstr ""