Consider using Django Jinja2 backend instead of calling jinja2.Environment directly

Django provides some helpers that could clean the notification code.

Source: https://github.com/kernelci/dashboard/pull/1646#discussion_r2614992961

Start with the discussion at https://github.com/kernelci/dashboard/pull/1646#discussion_r2614992961, then locate the notification code that calls jinja2.Environment directly. Compare that usage with Django's provided helpers; the work is done when the notification code uses the agreed Django Jinja2 backend approach and its existing behavior remains covered.

Written by the indexing model from the issue text.