Use helpers instead of URLs in switch checkboxes

Absolute URLs may be potentially breaking functionality, eg in case of
sub-directory installation.

Fixes https://github.com/openSUSE/osem/issues/2472

Co-authored-by: Ana María Martínez Gómez <anamaria@martinezgomez.name>

app/views/admin/users/_form.html.haml

@@ -6,12 +6,12 @@
           Confirmed?
         - if can? :toggle_confirmation, @user
           = check_box_tag @user.id, @user.id, @user.confirmed?,
-            url: "/admin/users/#{@user.id}/toggle_confirmation?user[to_confirm]=",
+            url: "#{toggle_confirmation_admin_user_path(@user.id)}?user[to_confirm]=",
             class: 'switch-checkbox',
             readonly: false
         - else
           = check_box_tag @user.id, @user.id, @user.confirmed?,
-            url: "/admin/users/#{@user.id}/toggle_confirmation?user[to_confirm]=",
+            url: "#{toggle_confirmation_admin_user_path(@user.id)}?user[to_confirm]=",
             class: 'switch-checkbox',
             readonly: true
     = f.input :is_admin, hint: 'An admin can create a new conference, manage users and make other users admins.'