Fix Django superuser creation failing with ImproperlyConfigured error (#9554)

* Initial plan

* Fix Django superuser creation by using manage.py shell

Co-authored-by: MickLesk <[email protected]>

* Add $STD prefix to superuser creation for consistency

Co-authored-by: MickLesk <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: MickLesk <[email protected]>

Author: Copilot

install/healthchecks-install.sh

@@ -89,7 +89,7 @@ $STD python manage.py migrate --noinput
 $STD python manage.py collectstatic --noinput
 $STD python manage.py compress
 
-python <<EOF
+$STD python manage.py shell <<EOF
 from django.contrib.auth import get_user_model
 User = get_user_model()
 if not User.objects.filter(email="${ADMIN_EMAIL}").exists():