Fix ast-grep config (nushell#16691)

The `sgconfig.yml` referred to the `ast-grep/utils` directory which is
not shared via the repository without a stub file in git


## Release notes summary - What our users need to know
N/A
## Tasks after submitting
- actually make the rules usable via `ast-grep scan` currently many
false positives due to lacking ignore annotations or incorrect
substitutions suggested.

Author: sholderbach