tests/systemd-networkd-wireguard: migrate to `make-test-python`
tests/systemd-networkd-wireguard: migrate to `make-test-python`

Updating `systemd-networkd-wireguard` to use the python test runner.

This change was purely syntactic. This migration did not require any
semantic change.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs